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annotate Lib/anydbm.py @ 79675:c0a2294de787 2.7

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Issue #16199: Backport 2to3 typo fix from 3.2.
author Chris Jerdonek <chris.jerdonek@gmail.com>
date Thu, 11 Oct 2012 16:15:46 -0700
parents 5c3f3d352e0a
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 """Generic interface to all dbm clones.
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2
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3 Instead of
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4
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5 import dbm
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6 d = dbm.open(file, 'w', 0666)
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7
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8 use
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9
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10 import anydbm
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11 d = anydbm.open(file, 'w')
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12
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13 The returned object is a dbhash, gdbm, dbm or dumbdbm object,
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14 dependent on the type of database being opened (determined by whichdb
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15 module) in the case of an existing dbm. If the dbm does not exist and
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16 the create or new flag ('c' or 'n') was specified, the dbm type will
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17 be determined by the availability of the modules (tested in the above
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18 order).
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19
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20 It has the following interface (key and data are strings):
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21
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22 d[key] = data # store data at key (may override data at
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23 # existing key)
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24 data = d[key] # retrieve data at key (raise KeyError if no
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25 # such key)
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26 del d[key] # delete data stored at key (raises KeyError
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27 # if no such key)
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28 flag = key in d # true if the key exists
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29 list = d.keys() # return a list of all existing keys (slow!)
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30
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31 Future versions may change the order in which implementations are
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32 tested for existence, and add interfaces to other dbm-like
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33 implementations.
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34 """
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35
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36 class error(Exception):
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37 pass
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38
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39 _names = ['dbhash', 'gdbm', 'dbm', 'dumbdbm']
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40 _errors = [error]
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41 _defaultmod = None
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42
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43 for _name in _names:
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44 try:
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45 _mod = __import__(_name)
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46 except ImportError:
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47 continue
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48 if not _defaultmod:
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49 _defaultmod = _mod
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50 _errors.append(_mod.error)
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51
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52 if not _defaultmod:
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53 raise ImportError, "no dbm clone found; tried %s" % _names
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54
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55 error = tuple(_errors)
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56
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57 def open(file, flag='r', mode=0666):
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58 """Open or create database at path given by *file*.
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59
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60 Optional argument *flag* can be 'r' (default) for read-only access, 'w'
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61 for read-write access of an existing database, 'c' for read-write access
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62 to a new or existing database, and 'n' for read-write access to a new
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63 database.
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64
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65 Note: 'r' and 'w' fail if the database doesn't exist; 'c' creates it
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66 only if it doesn't exist; and 'n' always creates a new database.
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67 """
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68
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69 # guess the type of an existing database
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70 from whichdb import whichdb
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71 result=whichdb(file)
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72 if result is None:
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73 # db doesn't exist
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74 if 'c' in flag or 'n' in flag:
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75 # file doesn't exist and the new
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76 # flag was used so use default type
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77 mod = _defaultmod
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78 else:
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79 raise error, "need 'c' or 'n' flag to open new db"
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80 elif result == "":
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81 # db type cannot be determined
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82 raise error, "db type could not be determined"
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83 else:
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84 mod = __import__(result)
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85 return mod.open(file, flag, mode)