cpython-lru_cache-weakref: Doc/lib/libcodecs.tex annotate

annotate Doc/lib/libcodecs.tex @ 25838:8540887bcec6 2.2

Backport of 2.183: Fix memory leak in add_subclass() found by NealN with valgrind.

author	Guido van Rossum <guido@python.org>
date	Fri, 18 Oct 2002 13:42:21 +0000
parents	376ee174ecd0
children	09db3f5d0bd0

rev	line source
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	1 \section{\module{codecs} ---
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	2 Codec registry and base classes}
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	3
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	4 \declaremodule{standard}{codecs}
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	5 \modulesynopsis{Encode and decode data and streams.}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	6 \moduleauthor{Marc-Andre Lemburg}{mal@lemburg.com}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	7 \sectionauthor{Marc-Andre Lemburg}{mal@lemburg.com}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	8
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	9
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	10 \index{Unicode}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	11 \index{Codecs}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	12 \indexii{Codecs}{encode}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	13 \indexii{Codecs}{decode}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	14 \index{streams}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	15 \indexii{stackable}{streams}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	16
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	17
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	18 This module defines base classes for standard Python codecs (encoders
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	19 and decoders) and provides access to the internal Python codec
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	20 registry which manages the codec lookup process.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	21
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	22 It defines the following functions:
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	23
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	24 \begin{funcdesc}{register}{search_function}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	25 Register a codec search function. Search functions are expected to
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	26 take one argument, the encoding name in all lower case letters, and
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	27 return a tuple of functions \code{(\var{encoder}, \var{decoder}, \var{stream_reader},
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	28 \var{stream_writer})} taking the following arguments:
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	29
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	30 \var{encoder} and \var{decoder}: These must be functions or methods
15186 b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	31 which have the same interface as the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	32 \method{encode()}/\method{decode()} methods of Codec instances (see
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	33 Codec Interface). The functions/methods are expected to work in a
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	34 stateless mode.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	35
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	36 \var{stream_reader} and \var{stream_writer}: These have to be
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	37 factory functions providing the following interface:
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	38
15186 b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	39 \code{factory(\var{stream}, \var{errors}='strict')}
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	40
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	41 The factory functions must return objects providing the interfaces
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	42 defined by the base classes \class{StreamWriter} and
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	43 \class{StreamReader}, respectively. Stream codecs can maintain
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	44 state.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	45
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	46 Possible values for errors are \code{'strict'} (raise an exception
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	47 in case of an encoding error), \code{'replace'} (replace malformed
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	48 data with a suitable replacement marker, such as \character{?}) and
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	49 \code{'ignore'} (ignore malformed data and continue without further
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	50 notice).
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	51
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	52 In case a search function cannot find a given encoding, it should
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	53 return \code{None}.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	54 \end{funcdesc}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	55
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	56 \begin{funcdesc}{lookup}{encoding}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	57 Looks up a codec tuple in the Python codec registry and returns the
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	58 function tuple as defined above.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	59
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	60 Encodings are first looked up in the registry's cache. If not found,
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	61 the list of registered search functions is scanned. If no codecs tuple
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	62 is found, a \exception{LookupError} is raised. Otherwise, the codecs
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	63 tuple is stored in the cache and returned to the caller.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	64 \end{funcdesc}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	65
19982 bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	66 To simply access to the various codecs, the module provides these
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	67 additional functions which use \function{lookup()} for the codec
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	68 lookup:
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	69
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	70 \begin{funcdesc}{getencoder}{encoding}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	71 Lookup up the codec for the given encoding and return its encoder
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	72 function.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	73
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	74 Raises a \exception{LookupError} in case the encoding cannot be found.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	75 \end{funcdesc}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	76
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	77 \begin{funcdesc}{getdecoder}{encoding}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	78 Lookup up the codec for the given encoding and return its decoder
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	79 function.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	80
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	81 Raises a \exception{LookupError} in case the encoding cannot be found.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	82 \end{funcdesc}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	83
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	84 \begin{funcdesc}{getreader}{encoding}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	85 Lookup up the codec for the given encoding and return its StreamReader
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	86 class or factory function.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	87
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	88 Raises a \exception{LookupError} in case the encoding cannot be found.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	89 \end{funcdesc}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	90
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	91 \begin{funcdesc}{getwriter}{encoding}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	92 Lookup up the codec for the given encoding and return its StreamWriter
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	93 class or factory function.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	94
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	95 Raises a \exception{LookupError} in case the encoding cannot be found.
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	96 \end{funcdesc}
bf4b1b08a2c6 Docs and News item for the codecs.py additions. Marc-André Lemburg <mal@egenix.com> parents: 16127 diff changeset	97
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	98 To simplify working with encoded files or stream, the module
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	99 also defines these utility functions:
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	100
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	101 \begin{funcdesc}{open}{filename, mode\optional{, encoding\optional{,
bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	102 errors\optional{, buffering}}}}
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	103 Open an encoded file using the given \var{mode} and return
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	104 a wrapped version providing transparent encoding/decoding.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	105
20580 376ee174ecd0 Use the \note and \warning macros where appropriate. Fred Drake <fdrake@acm.org> parents: 19982 diff changeset	106 \note{The wrapped version will only accept the object format
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	107 defined by the codecs, i.e.\ Unicode objects for most built-in
bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	108 codecs. Output is also codec-dependent and will usually be Unicode as
20580 376ee174ecd0 Use the \note and \warning macros where appropriate. Fred Drake <fdrake@acm.org> parents: 19982 diff changeset	109 well.}
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	110
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	111 \var{encoding} specifies the encoding which is to be used for the
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	112 the file.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	113
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	114 \var{errors} may be given to define the error handling. It defaults
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	115 to \code{'strict'} which causes a \exception{ValueError} to be raised
bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	116 in case an encoding error occurs.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	117
12274 559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	118 \var{buffering} has the same meaning as for the built-in
559b25a79032 Make sure the \declaremodule uses the right name for the module! Fred Drake <fdrake@acm.org> parents: 12260 diff changeset	119 \function{open()} function. It defaults to line buffered.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	120 \end{funcdesc}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	121
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	122 \begin{funcdesc}{EncodedFile}{file, input\optional{,
bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	123 output\optional{, errors}}}
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	124 Return a wrapped version of file which provides transparent
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	125 encoding translation.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	126
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	127 Strings written to the wrapped file are interpreted according to the
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	128 given \var{input} encoding and then written to the original file as
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	129 strings using the \var{output} encoding. The intermediate encoding will
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	130 usually be Unicode but depends on the specified codecs.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	131
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	132 If \var{output} is not given, it defaults to \var{input}.
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	133
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	134 \var{errors} may be given to define the error handling. It defaults to
13696 bb364d6f9f69 Fix small typos and markup consistency nits. Fred Drake <fdrake@acm.org> parents: 12274 diff changeset	135 \code{'strict'}, which causes \exception{ValueError} to be raised in case
12260 8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	136 an encoding error occurs.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	137 \end{funcdesc}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	138
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	139 The module also provides the following constants which are useful
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	140 for reading and writing to platform dependent files:
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	141
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	142 \begin{datadesc}{BOM}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	143 \dataline{BOM_BE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	144 \dataline{BOM_LE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	145 \dataline{BOM32_BE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	146 \dataline{BOM32_LE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	147 \dataline{BOM64_BE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	148 \dataline{BOM64_LE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	149 These constants define the byte order marks (BOM) used in data
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	150 streams to indicate the byte order used in the stream or file.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	151 \constant{BOM} is either \constant{BOM_BE} or \constant{BOM_LE}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	152 depending on the platform's native byte order, while the others
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	153 represent big endian (\samp{_BE} suffix) and little endian
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	154 (\samp{_LE} suffix) byte order using 32-bit and 64-bit encodings.
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	155 \end{datadesc}
8c0f863ba50c Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: diff changeset	156
16127 6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	157
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	158 \begin{seealso}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	159 \seeurl{http://sourceforge.net/projects/python-codecs/}{A
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	160 SourceForge project working on additional support for Asian
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	161 codecs for use with Python. They are in the early stages of
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	162 development at the time of this writing --- look in their
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	163 FTP area for downloadable files.}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	164 \end{seealso}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	165
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	166
15186 b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	167 \subsection{Codec Base Classes}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	168
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	169 The \module{codecs} defines a set of base classes which define the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	170 interface and can also be used to easily write you own codecs for use
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	171 in Python.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	172
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	173 Each codec has to define four interfaces to make it usable as codec in
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	174 Python: stateless encoder, stateless decoder, stream reader and stream
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	175 writer. The stream reader and writers typically reuse the stateless
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	176 encoder/decoder to implement the file protocols.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	177
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	178 The \class{Codec} class defines the interface for stateless
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	179 encoders/decoders.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	180
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	181 To simplify and standardize error handling, the \method{encode()} and
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	182 \method{decode()} methods may implement different error handling
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	183 schemes by providing the \var{errors} string argument. The following
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	184 string values are defined and implemented by all standard Python
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	185 codecs:
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	186
16127 6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	187 \begin{tableii}{l\|l}{code}{Value}{Meaning}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	188 \lineii{'strict'}{Raise \exception{ValueError} (or a subclass);
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	189 this is the default.}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	190 \lineii{'ignore'}{Ignore the character and continue with the next.}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	191 \lineii{'replace'}{Replace with a suitable replacement character;
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	192 Python will use the official U+FFFD REPLACEMENT
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	193 CHARACTER for the built-in Unicode codecs.}
6f1fd8500398 Added link to the "Python Codecs" project at SourceForge. Fred Drake <fdrake@acm.org> parents: 15186 diff changeset	194 \end{tableii}
15186 b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	195
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	196
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	197 \subsubsection{Codec Objects \label{codec-objects}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	198
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	199 The \class{Codec} class defines these methods which also define the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	200 function interfaces of the stateless encoder and decoder:
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	201
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	202 \begin{methoddesc}{encode}{input\optional{, errors}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	203 Encodes the object \var{input} and returns a tuple (output object,
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	204 length consumed).
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	205
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	206 \var{errors} defines the error handling to apply. It defaults to
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	207 \code{'strict'} handling.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	208
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	209 The method may not store state in the \class{Codec} instance. Use
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	210 \class{StreamCodec} for codecs which have to keep state in order to
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	211 make encoding/decoding efficient.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	212
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	213 The encoder must be able to handle zero length input and return an
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	214 empty object of the output object type in this situation.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	215 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	216
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	217 \begin{methoddesc}{decode}{input\optional{, errors}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	218 Decodes the object \var{input} and returns a tuple (output object,
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	219 length consumed).
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	220
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	221 \var{input} must be an object which provides the \code{bf_getreadbuf}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	222 buffer slot. Python strings, buffer objects and memory mapped files
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	223 are examples of objects providing this slot.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	224
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	225 \var{errors} defines the error handling to apply. It defaults to
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	226 \code{'strict'} handling.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	227
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	228 The method may not store state in the \class{Codec} instance. Use
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	229 \class{StreamCodec} for codecs which have to keep state in order to
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	230 make encoding/decoding efficient.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	231
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	232 The decoder must be able to handle zero length input and return an
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	233 empty object of the output object type in this situation.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	234 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	235
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	236 The \class{StreamWriter} and \class{StreamReader} classes provide
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	237 generic working interfaces which can be used to implement new
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	238 encodings submodules very easily. See \module{encodings.utf_8} for an
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	239 example on how this is done.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	240
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	241
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	242 \subsubsection{StreamWriter Objects \label{stream-writer-objects}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	243
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	244 The \class{StreamWriter} class is a subclass of \class{Codec} and
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	245 defines the following methods which every stream writer must define in
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	246 order to be compatible to the Python codec registry.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	247
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	248 \begin{classdesc}{StreamWriter}{stream\optional{, errors}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	249 Constructor for a \class{StreamWriter} instance.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	250
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	251 All stream writers must provide this constructor interface. They are
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	252 free to add additional keyword arguments, but only the ones defined
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	253 here are used by the Python codec registry.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	254
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	255 \var{stream} must be a file-like object open for writing (binary)
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	256 data.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	257
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	258 The \class{StreamWriter} may implement different error handling
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	259 schemes by providing the \var{errors} keyword argument. These
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	260 parameters are defined:
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	261
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	262 \begin{itemize}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	263 \item \code{'strict'} Raise \exception{ValueError} (or a subclass);
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	264 this is the default.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	265 \item \code{'ignore'} Ignore the character and continue with the next.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	266 \item \code{'replace'} Replace with a suitable replacement character
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	267 \end{itemize}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	268 \end{classdesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	269
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	270 \begin{methoddesc}{write}{object}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	271 Writes the object's contents encoded to the stream.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	272 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	273
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	274 \begin{methoddesc}{writelines}{list}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	275 Writes the concatenated list of strings to the stream (possibly by
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	276 reusing the \method{write()} method).
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	277 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	278
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	279 \begin{methoddesc}{reset}{}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	280 Flushes and resets the codec buffers used for keeping state.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	281
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	282 Calling this method should ensure that the data on the output is put
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	283 into a clean state, that allows appending of new fresh data without
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	284 having to rescan the whole stream to recover state.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	285 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	286
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	287 In addition to the above methods, the \class{StreamWriter} must also
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	288 inherit all other methods and attribute from the underlying stream.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	289
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	290
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	291 \subsubsection{StreamReader Objects \label{stream-reader-objects}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	292
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	293 The \class{StreamReader} class is a subclass of \class{Codec} and
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	294 defines the following methods which every stream reader must define in
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	295 order to be compatible to the Python codec registry.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	296
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	297 \begin{classdesc}{StreamReader}{stream\optional{, errors}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	298 Constructor for a \class{StreamReader} instance.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	299
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	300 All stream readers must provide this constructor interface. They are
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	301 free to add additional keyword arguments, but only the ones defined
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	302 here are used by the Python codec registry.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	303
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	304 \var{stream} must be a file-like object open for reading (binary)
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	305 data.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	306
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	307 The \class{StreamReader} may implement different error handling
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	308 schemes by providing the \var{errors} keyword argument. These
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	309 parameters are defined:
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	310
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	311 \begin{itemize}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	312 \item \code{'strict'} Raise \exception{ValueError} (or a subclass);
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	313 this is the default.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	314 \item \code{'ignore'} Ignore the character and continue with the next.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	315 \item \code{'replace'} Replace with a suitable replacement character.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	316 \end{itemize}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	317 \end{classdesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	318
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	319 \begin{methoddesc}{read}{\optional{size}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	320 Decodes data from the stream and returns the resulting object.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	321
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	322 \var{size} indicates the approximate maximum number of bytes to read
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	323 from the stream for decoding purposes. The decoder can modify this
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	324 setting as appropriate. The default value -1 indicates to read and
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	325 decode as much as possible. \var{size} is intended to prevent having
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	326 to decode huge files in one step.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	327
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	328 The method should use a greedy read strategy meaning that it should
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	329 read as much data as is allowed within the definition of the encoding
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	330 and the given size, e.g. if optional encoding endings or state
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	331 markers are available on the stream, these should be read too.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	332 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	333
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	334 \begin{methoddesc}{readline}{[size]}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	335 Read one line from the input stream and return the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	336 decoded data.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	337
20580 376ee174ecd0 Use the \note and \warning macros where appropriate. Fred Drake <fdrake@acm.org> parents: 19982 diff changeset	338 Unlike the \method{readlines()} method, this method inherits
15186 b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	339 the line breaking knowledge from the underlying stream's
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	340 \method{readline()} method -- there is currently no support for line
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	341 breaking using the codec decoder due to lack of line buffering.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	342 Sublcasses should however, if possible, try to implement this method
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	343 using their own knowledge of line breaking.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	344
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	345 \var{size}, if given, is passed as size argument to the stream's
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	346 \method{readline()} method.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	347 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	348
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	349 \begin{methoddesc}{readlines}{[sizehint]}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	350 Read all lines available on the input stream and return them as list
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	351 of lines.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	352
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	353 Line breaks are implemented using the codec's decoder method and are
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	354 included in the list entries.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	355
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	356 \var{sizehint}, if given, is passed as \var{size} argument to the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	357 stream's \method{read()} method.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	358 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	359
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	360 \begin{methoddesc}{reset}{}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	361 Resets the codec buffers used for keeping state.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	362
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	363 Note that no stream repositioning should take place. This method is
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	364 primarily intended to be able to recover from decoding errors.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	365 \end{methoddesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	366
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	367 In addition to the above methods, the \class{StreamReader} must also
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	368 inherit all other methods and attribute from the underlying stream.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	369
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	370 The next two base classes are included for convenience. They are not
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	371 needed by the codec registry, but may provide useful in practice.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	372
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	373
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	374 \subsubsection{StreamReaderWriter Objects \label{stream-reader-writer}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	375
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	376 The \class{StreamReaderWriter} allows wrapping streams which work in
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	377 both read and write modes.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	378
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	379 The design is such that one can use the factory functions returned by
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	380 the \function{lookup()} function to construct the instance.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	381
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	382 \begin{classdesc}{StreamReaderWriter}{stream, Reader, Writer, errors}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	383 Creates a \class{StreamReaderWriter} instance.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	384 \var{stream} must be a file-like object.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	385 \var{Reader} and \var{Writer} must be factory functions or classes
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	386 providing the \class{StreamReader} and \class{StreamWriter} interface
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	387 resp.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	388 Error handling is done in the same way as defined for the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	389 stream readers and writers.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	390 \end{classdesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	391
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	392 \class{StreamReaderWriter} instances define the combined interfaces of
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	393 \class{StreamReader} and \class{StreamWriter} classes. They inherit
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	394 all other methods and attribute from the underlying stream.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	395
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	396
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	397 \subsubsection{StreamRecoder Objects \label{stream-recoder-objects}}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	398
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	399 The \class{StreamRecoder} provide a frontend - backend view of
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	400 encoding data which is sometimes useful when dealing with different
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	401 encoding environments.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	402
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	403 The design is such that one can use the factory functions returned by
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	404 the \function{lookup()} function to construct the instance.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	405
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	406 \begin{classdesc}{StreamRecoder}{stream, encode, decode,
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	407 Reader, Writer, errors}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	408 Creates a \class{StreamRecoder} instance which implements a two-way
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	409 conversion: \var{encode} and \var{decode} work on the frontend (the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	410 input to \method{read()} and output of \method{write()}) while
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	411 \var{Reader} and \var{Writer} work on the backend (reading and
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	412 writing to the stream).
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	413
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	414 You can use these objects to do transparent direct recodings from
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	415 e.g.\ Latin-1 to UTF-8 and back.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	416
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	417 \var{stream} must be a file-like object.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	418
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	419 \var{encode}, \var{decode} must adhere to the \class{Codec}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	420 interface, \var{Reader}, \var{Writer} must be factory functions or
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	421 classes providing objects of the the \class{StreamReader} and
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	422 \class{StreamWriter} interface respectively.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	423
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	424 \var{encode} and \var{decode} are needed for the frontend
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	425 translation, \var{Reader} and \var{Writer} for the backend
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	426 translation. The intermediate format used is determined by the two
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	427 sets of codecs, e.g. the Unicode codecs will use Unicode as
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	428 intermediate encoding.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	429
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	430 Error handling is done in the same way as defined for the
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	431 stream readers and writers.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	432 \end{classdesc}
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	433
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	434 \class{StreamRecoder} instances define the combined interfaces of
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	435 \class{StreamReader} and \class{StreamWriter} classes. They inherit
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	436 all other methods and attribute from the underlying stream.
b2892cbc63db Marc-Andre Lemburg <mal@lemburg.com>: Fred Drake <fdrake@acm.org> parents: 13696 diff changeset	437

Mercurial > cpython-lru_cache-weakref

annotate Doc/lib/libcodecs.tex @ 25838:8540887bcec6 2.2