How Can I Perform Effective Type Checking in Python?

Type Checking in Python: A Comprehensive Guide

Python provides various ways to determine the type of an object. This article presents the canonical approaches to check if an object belongs to a specific type or inherits from a given superclass.

Checking Type Inheritance with isinstance

To ascertain if an object is an instance of a particular type or its subclasses, utilize the isinstance function. For instance, to verify if o is a string or derives from it, employ the following syntax:

if isinstance(o, str):
    # Code to execute when o is an instance of str

Exact Type Checking with type

Alternatively, if you need to determine the exact type of o without considering subclasses, utilize the type function. This approach ensures that o is precisely of the str type:

if type(o) is str:
    # Code to execute when o is exactly of type str

Handling Strings in Python 2

In Python 2, handling string comparisons is slightly different. To check if o is a string, use isinstance with the basestring type, which encompasses both str and unicode strings:

if isinstance(o, basestring):
    # Code to execute when o is a string or unicode

Alternatively, you can employ a tuple of types to ascertain if o is an instance of any subclass of str or unicode:

if isinstance(o, (str, unicode)):
    # Code to execute when o is an instance of str or unicode

Comprehending these approaches will empower you to conduct meticulous type checks in your Python code, ensuring the desired behavior and preventing potential errors.

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