Determine if Python variable is an instance of a built-in type

python variables instance
Aleksandr Motsjonov picture Aleksandr Motsjonov · Aug 24, 2009 · Viewed 14.3k times · Source

I need to determine if a given Python variable is an instance of native type: str, int, float, bool, list, dict and so on. Is there elegant way to doing it?

Or is this the only way: 

if myvar in (str, int, float, bool):
    # do something

Answer

glarrain picture glarrain · Jul 22, 2013

This is an old question but it seems none of the answers actually answer the specific question: "(How-to) Determine if Python variable is an instance of a built-in type". Note that it's not "[...] of a specific/given built-in type" but of a.

The proper way to determine if a given object is an instance of a buil-in type/class is to check if the type of the object happens to be defined in the module __builtin__.

def is_builtin_class_instance(obj):
    return obj.__class__.__module__ == '__builtin__'

Warning: if obj is a class and not an instance, no matter if that class is built-in or not, True will be returned since a class is also an object, an instance of type (i.e. AnyClass.__class__ is type).

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