Python Variable Scope

Python - Variable Scope:

Variable scope refers to the region of a program where a variable is accessible. Understanding scope is crucial for writing clean, bug-free code. In Python, there are mainly two types of variable scope: global scope and local scope.

1. Global Scope:

⤏ Variables declared outside of any function or class have global scope.

⤏ They can be accessed from anywhere within the program, including inside functions and classes.

⤏ To modify a global variable from within a function, you need to use the 'global' keyword.

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# Python variable scope: Global
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x = 10 # Global variable
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def func():
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print(x) # Accessing global variable
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func() # Output: 10

10

2. Local Scope:

⤏ Variables declared within a function or a class have local scope.

⤏ They can only be accessed from within that function or class.

⤏ Variables with the same name can exist both globally and locally without affecting each other.

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def func():
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y = 20 # Local variable
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print(y)
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func() # Output: 20
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# Accessing local variable outside the function will result in NameError
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print(y) # NameError: name 'y' is not defined

[Error] NameError: name 'y' is not defined

However, Python also supports a concept called "enclosing scope," which comes into play with nested functions. In the case of nested functions, a variable declared in an outer function is accessible in the inner function.

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# Python variable scope: Local
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def outer_func():
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z = 30 # Enclosing scope variable
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def inner_func():
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print(z) # Accessing enclosing scope variable
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inner_func()
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outer_func() # Output: 30

30

Note: You can also use the 'nonlocal' keyword, which allows you to modify variables in the enclosing scope from within nested functions.

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nonlocal x
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x = 20 # Modifying variable in the enclosing scope