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How import works in Python

 


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How import works in Python

The import statement in Python is used to include the definitions (functions, variables, classes) from a module into the current namespace, allowing you to use those definitions in your code.

1. Basic import

The most common way to use import is:


import module_name

This statement imports the entire module and you can access its definitions using the module_name prefix.

2. Import specific definitions

You can also import specific definitions from a module:


from module_name import definition1, definition2

This allows you to use definition1 and definition2 directly without the module prefix.

3. Import all definitions

To import all definitions from a module, use:


from module_name import *

This imports all definitions from the module into the current namespace, but it's generally not recommended due to potential name conflicts.

4. Import with alias

Modules can be imported with an alias using the as keyword:


import module_name as alias

This allows you to use alias instead of module_name to access the module's definitions.

5. Importing from a package

If the module is part of a package, you can import it using the dot notation:


import package_name.module_name

Or import specific definitions from a module within a package:


from package_name.module_name import definition

6. Reloading a module

To reload a module that has already been imported, use the reload function from the importlib module:


from importlib import reload
reload(module_name)

7. Importing in Python 2 vs Python 3

In Python 2, relative imports are implicit. In Python 3, relative imports must be explicit using a dot (.) notation:


# Python 3 relative import
from .module import definition

8. Importing from a different Python file

To import classes and functions from a different Python file (e.g., from code.py to main.py), you can use the following syntax:


from code import ClassName, function_name

This imports the ClassName class and the function_name function from the code.py file. You can then use them in your main.py file:


# Importing from code.py to main.py
from code import ClassName, function_name

# Creating an instance of the class
instance = ClassName()

# Using the imported function
function_name()
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