使用了c语言实现的函数

partial

可能的实现方式

def partial(func, *args, **keywords):
    def newfunc(*fargs, **fkeywords):
        newkeywords = keywords.copy()
        newkeywords.update(fkeywords)
        return func(*(args + fargs), **newkeywords)
    newfunc.func = func
    newfunc.args = args
    newfunc.keywords = keywords
    return newfunc

reduce

reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) 即 ((((1+2)+3)+4)+5)

cmp_to_key

把老形式的比较函数转换为key函数
(需要接收新形式key函数的函数：sorted min max heapq itertools.groupby)

老形式的比较函数：
接收两个参数，比较他们，返回-1 0 1这样来确定。

sorted(iterable, key=cmp_to_key(locale.strcoll))  # locale-aware sort order

total_ordering

包裹的类只要定义一个或多个比较函数即可生成出其余的函数来
lt, le, gt, ge 这几个函数必须要定义一个

使用

@total_ordering
class Student:
    def __eq__(self, other):
        return ((self.lastname.lower(), self.firstname.lower()) ==
                (other.lastname.lower(), other.firstname.lower()))
    def __lt__(self, other):
        return ((self.lastname.lower(), self.firstname.lower()) <
                (other.lastname.lower(), other.firstname.lower()))

update_wrapper

更新装饰器的属性使得装饰器像原来函数一样

源码

WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')
WRAPPER_UPDATES = ('__dict__',)
def update_wrapper(wrapper,
                wrapped,
                assigned = WRAPPER_ASSIGNMENTS,
                updated = WRAPPER_UPDATES):

    for attr in assigned:
        setattr(wrapper, attr, getattr(wrapped, attr))
    for attr in updated:
        getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
   
    return wrapper

wrapper为装饰器，wrapped为被装饰的函数，assigned为赋值，updated为更新

wraps

wraps就是使用partial实现的快捷方式，用于装饰器的

def wraps(wrapped[, assigned][, updated]):
    return partial(update_wrapper, wrapped=wrapped, assigned=assigned, updated=updated)

例子

>>> from functools import wraps
>>> def my_decorator(f):
...     @wraps(f)
...     def wrapper(*args, **kwds):
...         print 'Calling decorated function'
...         return f(*args, **kwds)
...     return wrapper

@my_decorator
... def example():
...     """Docstring"""
...     print 'Called example function'
...
>>> example()
Calling decorated function
Called example function
>>> example.__name__
'example'
>>> example.__doc__
'Docstring'

使用wraps会自动把docstr和funcname用起来