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Python中callable的理解?

>Python has a more general concept of callable object, that is every object that can be called, which means applied on some data.

我在读一篇博客的时候看到这句话,作者认为Python对callable的概念是比较宽泛的,任何对象都可以被调用。这样说对么?如何理解?

Python的内建的callable()函数可以用来检测是否能够调用,如果所有对象都可以call,那么为什么还有检测呢?


同意 @charliecui 说的 python的Object是一个泛型概念

对于文中的话,我理解是 python 中一切都是对象,这些对象都是 object 的实例,Python创建对象是通过 type方式,这个type又有一个 __call__方法,实现了这个方法,最终的对象就能被调用(callable)。

大概意思就是这些对象通过技巧都是可以调用的,通过使这些对象可以调用来处理一些数据。

简单的用法就是类似 web 框架中的路由 (Router), 使得 Router直接装饰,不需要额外的创建实例来创建对象,而是让自身就是一个可以调用的对象。

python
class Router(): def __call__(self): pass @Router('/index') def index(): pass

具体实现可以参考 可以参考 https://github.com/nod/tornroutes/blob/master/tornroutes/__init__.py

一个给 tornado 实现 routerdecorator


见stackoverflow上有关python的callable的讨论http://stackoverflow.com/questions/111234/what-is-a-callable-in-python

python的Object是一个泛型概念,而不是特制类的对象,比如函数也可以是一个Object,类也可以是Object。你看下callable()的原型,定义在builtin.py中

def callable(p_object): # real signature unknown; restored from __doc__
    """
    callable(object) -> bool

    Return whether the object is callable (i.e., some kind of function).
    Note that classes are callable, as are instances with a __call__() method.
    """
    return False

仔细一看,这是英语断句的问题啊

englishPython has [a more general concept] of [[callable object], that is every [object that can be called, which means applied on some data]]

不是“每个对象都能被调用”,而是“callable object”是“所有能被调用的对象”,最后那个从句解释调用的概念是“被应用于数据”。

Python has a concept

Python has a more general concept

Python has a more general concept of callable object

Python has a more general concept of callable object, that is every object that can be called

Python has a more general concept of callable object, that is every object that can be called, which means applied on some data

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