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