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annotate Lib/functools.py @ 80661:94de77bd0b4b 2.7

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Issue #16194: document imp.load_dynamic problems when read several extension modules from the same binary object file.
author Andrew Svetlov <andrew.svetlov@gmail.com>
date Thu, 29 Nov 2012 19:51:28 +0200
parents 136298326897
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 """functools.py - Tools for working with functions and callable objects
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2 """
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3 # Python module wrapper for _functools C module
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4 # to allow utilities written in Python to be added
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5 # to the functools module.
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6 # Written by Nick Coghlan <ncoghlan at gmail.com>
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7 # Copyright (C) 2006 Python Software Foundation.
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8 # See C source code for _functools credits/copyright
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9
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10 from _functools import partial, reduce
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11
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12 # update_wrapper() and wraps() are tools to help write
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13 # wrapper functions that can handle naive introspection
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14
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15 WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')
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16 WRAPPER_UPDATES = ('__dict__',)
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17 def update_wrapper(wrapper,
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18 wrapped,
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19 assigned = WRAPPER_ASSIGNMENTS,
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20 updated = WRAPPER_UPDATES):
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21 """Update a wrapper function to look like the wrapped function
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22
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23 wrapper is the function to be updated
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24 wrapped is the original function
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25 assigned is a tuple naming the attributes assigned directly
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26 from the wrapped function to the wrapper function (defaults to
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27 functools.WRAPPER_ASSIGNMENTS)
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28 updated is a tuple naming the attributes of the wrapper that
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29 are updated with the corresponding attribute from the wrapped
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30 function (defaults to functools.WRAPPER_UPDATES)
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31 """
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32 for attr in assigned:
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33 setattr(wrapper, attr, getattr(wrapped, attr))
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34 for attr in updated:
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35 getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
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36 # Return the wrapper so this can be used as a decorator via partial()
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37 return wrapper
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38
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39 def wraps(wrapped,
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40 assigned = WRAPPER_ASSIGNMENTS,
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41 updated = WRAPPER_UPDATES):
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42 """Decorator factory to apply update_wrapper() to a wrapper function
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43
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44 Returns a decorator that invokes update_wrapper() with the decorated
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45 function as the wrapper argument and the arguments to wraps() as the
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46 remaining arguments. Default arguments are as for update_wrapper().
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47 This is a convenience function to simplify applying partial() to
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48 update_wrapper().
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49 """
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50 return partial(update_wrapper, wrapped=wrapped,
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51 assigned=assigned, updated=updated)
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52
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53 def total_ordering(cls):
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54 """Class decorator that fills in missing ordering methods"""
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55 convert = {
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56 '__lt__': [('__gt__', lambda self, other: not (self < other or self == other)),
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57 ('__le__', lambda self, other: self < other or self == other),
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58 ('__ge__', lambda self, other: not self < other)],
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59 '__le__': [('__ge__', lambda self, other: not self <= other or self == other),
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60 ('__lt__', lambda self, other: self <= other and not self == other),
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61 ('__gt__', lambda self, other: not self <= other)],
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62 '__gt__': [('__lt__', lambda self, other: not (self > other or self == other)),
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63 ('__ge__', lambda self, other: self > other or self == other),
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64 ('__le__', lambda self, other: not self > other)],
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65 '__ge__': [('__le__', lambda self, other: (not self >= other) or self == other),
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66 ('__gt__', lambda self, other: self >= other and not self == other),
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67 ('__lt__', lambda self, other: not self >= other)]
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68 }
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69 roots = set(dir(cls)) & set(convert)
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70 if not roots:
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71 raise ValueError('must define at least one ordering operation: < > <= >=')
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72 root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__
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73 for opname, opfunc in convert[root]:
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74 if opname not in roots:
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75 opfunc.__name__ = opname
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76 opfunc.__doc__ = getattr(int, opname).__doc__
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77 setattr(cls, opname, opfunc)
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78 return cls
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79
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80 def cmp_to_key(mycmp):
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81 """Convert a cmp= function into a key= function"""
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82 class K(object):
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83 __slots__ = ['obj']
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84 def __init__(self, obj, *args):
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85 self.obj = obj
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86 def __lt__(self, other):
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87 return mycmp(self.obj, other.obj) < 0
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88 def __gt__(self, other):
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89 return mycmp(self.obj, other.obj) > 0
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90 def __eq__(self, other):
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91 return mycmp(self.obj, other.obj) == 0
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92 def __le__(self, other):
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93 return mycmp(self.obj, other.obj) <= 0
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94 def __ge__(self, other):
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95 return mycmp(self.obj, other.obj) >= 0
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96 def __ne__(self, other):
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97 return mycmp(self.obj, other.obj) != 0
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98 def __hash__(self):
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99 raise TypeError('hash not implemented')
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100 return K