python: isinstance

isinstance(object, classinfo)

Return true if the object argument is an instance of the classinfo argument, or of a (direct or indirect) subclass thereof. Also return true ifclassinfo is a type object and object is an object of that type. Ifobject is not a class instance or an object of the given type, the function always returns false. Ifclassinfo is neither a class object nor a type object, it may be a tuple of class or type objects, or may recursively contain other such tuples (other sequence types are not accepted). Ifclassinfo is not a class, type, or tuple of classes, types, and such tuples, aTypeError exception is raised. Changed in version 2.2: Support for a tuple of type information was added.

Python可以得到一个对象的类型 ，利用type函数：

>>>lst = [1, 2, 3]
>>>type(lst)
<type 'list'>

不仅如此，还可以利用isinstance函数，来判断一个对象是否是一个已知的类型。

isinstance说明如下:

    isinstance(object, class-or-type-or-tuple) -> bool
   
    Return whether an object is an instance of a class or of a subclass thereof.
    With a type as second argument, return whether that is the object's type.
    The form using a tuple, isinstance(x, (A, B, ...)), is a shortcut for
    isinstance(x, A) or isinstance(x, B) or ... (etc.).

其第一个参数为对象，第二个为类型名或类型名的一个列表。其返回值为布尔型。若对象的类型与参数二的类型相同则返回True。若参数二为一个元组，则若对象类型与元组中类型名之一相同即返回True。

>>>isinstance(lst, list)
True

>>>isinstance(lst, (int, str, list))
True

>>>isinstance(lst, (int, str, list))
True