Python locals() Built in Function

The locals() function in Python returns a dictionary containing the current local symbol table. A symbol table contains necessary information about the current program, such as variable names and values. The locals() function can be used to access or modify local variables inside a function or a class.

Here are some examples of using locals() function in Python:

Using locals() function in Python

# This example prints the local symbol table of the global scope
x = 10
y = 20
print(locals())
# Output: {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x0000021E9F8A7D30>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, 'x': 10, 'y': 20}

Using Python locals() function inside local scope

# This example prints the local symbol table of a function
def foo():
    a = 1
    b = 2
    print(locals())

foo()
# Output: {'a': 1, 'b': 2}

Updating dictionary values by Python locals() Function

# This example modifies the value of a local variable using locals()
def bar():
    c = 3
    d = 4
    print(c) # Output: 3
    locals()['c'] = 5 # Change the value of c to 5 using locals()
    print(c) # Output: 5

bar()

Python locals() function for global environment

# This example shows that locals() and globals() return the same dictionary in the global scope
e = 6
f = 7
print(locals() is globals()) # Output: True

Using locals() function inside a class

# This example shows how to use locals() to return the variables and methods of a class
class Test:
    def __init__(self):
        self.g = 8
        self.h = 9
    
    def show(self):
        print(locals())

t = Test()
t.show()
# Output: {'self': <__main__.Test object at 0x0000021E9F8B6C70>, 'g': 8, 'h': 9}

Using locals() with list comprehension

# This example shows how to use locals() with list comprehension to filter out variables starting with '_'
i = "Hello"
j = "World"
k = [key for key in locals().keys() if not key.startswith('_')]
print(k)
# Output: ['i', 'j']

If you have any questions about this code, you can drop a line in comment.

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