Python: Using builtin functions globals(), locals(), vars()

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Using globals(), locals() & vars() in Python

Using globals(), locals() & vars() in Python

globals()

The builtin globals() function returns a dictionary containing objects accessible anywhere in the program.

>>> help(globals)
Help on built-in function globals in module builtins:

globals(...)
    globals() -> dictionary
    
    Return the dictionary containing the current scope's global variables.

### EXAMPLES ###
>>> aGlobalVariable = 'accessible everywhere.'
>>> print(globals())
{'__builtins__': <module 'builtins' (built-in)>, '__spec__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, 'aGlobalVariable': 'accessible everywhere.', '__name__': '__main__', '__doc__': None}
>>> def aConfinedPieceOfCode():
	aLocalVariable = 'accessible only locally.'
	print(globals())
	
>>> aConfinedPieceOfCode()
{'__builtins__': <module 'builtins' (built-in)>, '__spec__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, 'aConfinedPieceOfCode': <function aConfinedPieceOfCode at 0x03159A08>, 'aGlobalVariable': 'accessible everywhere.', '__name__': '__main__', '__doc__': None}

>>> 'aGlobalVariable' in globals()
True

---

locals()

The builtin locals() function returns a dictionary containing objects accessible only in the current scope.

>>> help(locals)
Help on built-in function locals in module builtins:

locals(...)
    locals() -> dictionary
    
    Update and return a dictionary containing the current scope's local variables.

	
### EXAMPLES ###
>>> aLocalVariable = 'accessible only locally.'
>>> print(locals())														# locals() of module
{'__builtins__': <module 'builtins' (built-in)>, '__spec__': None, '__package__': None, '__doc__': None, 'aLocalVariable': 'accessible only locally.', '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__name__': '__main__'}

>>> def aConfinedPieceOfCode():
	anotherLocalVariable = 'accessible only locally; present inside a function.'
	
	print("Printing dictionary of local objects:", locals())			# locals() of this scope.
	
	if 'anotherLocalVariable' in locals():
		print("Present.")

		
>>> aConfinedPieceOfCode()
Printing dictionary of local objects: {'anotherLocalVariable': 'accessible only locally; present inside a function.'}
Present.

Bear in mind that any top-level code in the module(i.e. code at the first indent level) goes in the local namespace of the module, constituting the global namespace.

---

vars()

The builtin function vars(obj) returns the dictionary of the attributes belonging to an instance/object as returned by the __dict__ attribute of the object. When used without an argument, it returns the the dictionary of local objects.

>>> help(vars)
Help on built-in function vars in module builtins:

vars(...)
    vars([object]) -> dictionary
    
    Without arguments, equivalent to locals().
    With an argument, equivalent to object.__dict__.

### EXAMPLES ###
>>> class Ethan():
	def __init__(self):
		self.name = 'Ethan'
		self.age = 23

>>> ethan = Ethan()

# Equivalent to object.__dict__ when called by passing an object.
>>> vars(ethan)
{'age': 23, 'name': 'Ethan'}
>>> ethan.__dict__
{'age': 23, 'name': 'Ethan'}

>>> 'age' in vars(ethan)
True

# Equivalent to locals() when called without arguments.
>>> vars()
{'__loader__': <class '_frozen_importlib.BuiltinImporter'>, 'Ethan': <class '__main__.Ethan'>, '__spec__': None, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__name__': '__main__', '__doc__': None, 'ethan': <__main__.Ethan object at 0x03090810>}

---

See also:

• Python 101
• Object Oriented Python
• Design Patterns in Python
• 50+ Handy Standard Library Modules
• 60+ Handy Third Library Modules
• 50+ Tips & Tricks for Python Developers
• 50+ Know-How(s) Every Pythonista Must Know