{"id":3292,"date":"2020-06-23T16:41:15","date_gmt":"2020-06-23T11:11:15","guid":{"rendered":"http:\/\/www.pythonpool.com\/?p=3292"},"modified":"2026-07-13T12:26:53","modified_gmt":"2026-07-13T06:56:53","slug":"init-python","status":"publish","type":"post","link":"https:\/\/www.pythonpool.com\/init-python\/","title":{"rendered":"Python __init__(): Initialize Objects, Inheritance, and Packages"},"content":{"rendered":"

Quick answer:<\/strong> __init__() is the initializer that runs after Python creates an instance. It receives self, prepares instance attributes, and validates starting state. __new__() is the method that creates the object, while __init__.py is a package file with a different purpose. Keep those three names distinct when explaining object construction and imports.<\/p>\n

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__new__ creates an instance and __init__ configures it; validate state, call super when required, and distinguish the method from a package’s __init__.py file.<\/figcaption><\/figure>\n

In Python, __init__()<\/code> is the initializer method that usually runs right after an object is created. It receives the new instance as self<\/code> and prepares that instance for normal use.<\/p>\n

Python programmers often call __init__()<\/code> a constructor because it is the method people write when they want setup code for a class. More precisely, object creation is handled by __new__()<\/code>, while __init__()<\/code> fills in the instance attributes and checks starting inputs.<\/p>\n

The official Python documentation for object.__init__<\/a> explains the data model rule. The Python classes tutorial<\/a> gives broader class background, and the packages tutorial<\/a> plus the regular packages reference<\/a> explain the separate __init__.py<\/code> file used by packages.<\/p>\n

The two names are easy to mix up: __init__()<\/code> is a method inside a class, while __init__.py<\/code> is a file inside a package directory. They are related by name, but they solve different problems.<\/p>\n

Use __init__()<\/code> when each instance needs its own starting data. Keep it focused on setup. If the method opens network connections, reads large files, or does slow work, creating the object becomes surprising and hard to test.<\/p>\n

A clean initializer also documents what the class expects at the moment an instance is born. Readers can scan its parameters, see which attributes are created, and understand the minimum data needed for a useful object. That makes later methods easier to follow because the basic object shape is established in one predictable place. Python has one __init__ method per class, so Python Multiple Constructors Guide<\/a> uses default arguments and class methods to provide alternate construction paths.<\/p>\n

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