python鏈中的源代碼在哪裏？

Question

我想在python itertools中看到chain的源代碼，但是這裏是我在源代碼中找到的東西？爲什麼他們都是「通過」？

class chain(object): 
    """ 
    chain(*iterables) --> chain object 

    Return a chain object whose .__next__() method returns elements from the 
    first iterable until it is exhausted, then elements from the next 
    iterable, until all of the iterables are exhausted. 
    """ 
    @classmethod 
    def from_iterable(cls, iterable): # real signature unknown; restored from __doc__ 
     """ 
     chain.from_iterable(iterable) --> chain object 

     Alternate chain() contructor taking a single iterable argument 
     that evaluates lazily. 
     """ 
     pass 

    def __getattribute__(self, *args, **kwargs): # real signature unknown 
     """ Return getattr(self, name). """ 
     pass 

    def __init__(self, *iterables): # real signature unknown; restored from __doc__ 
     pass 

    def __iter__(self, *args, **kwargs): # real signature unknown 
     """ Implement iter(self). """ 
     pass 

    @staticmethod # known case of __new__ 
    def __new__(*args, **kwargs): # real signature unknown 
     """ Create and return a new object. See help(type) for accurate signature. """ 
     pass 

Answer 1

您看到的類可能是另一個模塊。 Itertools和許多其他內置函數都是用編譯後的c語言編寫的。你可以在這裏閱讀CPython的代碼 https://github.com/python/cpython/blob/3.6/Modules/itertoolsmodule.c#L1792

和迭代工具文檔中，它指出在鏈功能大致相當於：

def chain(*iterables): 
    # chain('ABC', 'DEF') --> A B C D E F 
    for it in iterables: 
     for element in it: 
      yield element