相当于Ruby'is_a？'的Python

Question

I'm wondering is there a Python Equivalent to Ruby's 'is_a?' method?

> "".is_a? String
=> true

Info:

is_a?(class) → true or false

Returns true if class is the class of obj, or if class is one of the superclasses of obj or modules included in obj.

Thank you.

Answer 1

It depends on exactly what part you want.

If you want to know whether foo is an instance of class C or any of its ancestors, then:

isinstance(foo, C)

If you want to know whether foo is an instance of C and only C , then:

type(foo) == C

Broadly speaking, frequent use of things like isinstance(...) or type(...) is a code smell because it means duck typing is broken, and Python relies heavily on that sort of contract. See, eg, isinstance considered harmful .

Answer 2

I've never used Ruby, but that functionality looks a lot like what isinstance does:

>>> a = "string"
>>> isinstance(a, str)
True
>>>

Also, in case you don't know, here is a reference on str .

Answer 3

有一个isinstance(a,b)函数来检查a是否为b类型。