Python Scope

• There are four scopes in python:
  • Local all names declared inside a function will be accessed from its local scope.
  • Enclosed : this the case when you define function inside another, then the names in the outer function scope will be accessed from inner function local scope .
  • Global : all names you defined in the top of the module are accessible from any part from code.
  • Built in : This scope contains names such as keywords, functions, exceptions, and other attributes that are built into Python

global statement

• when you access a global name from a local scope you cant update it unless you declare it as global . it assumed it as a local variable. ```python var = 100 # A global variable def increment(): var = var + 1 # Try to update a global variable

increment() UnboundLocalError: local variable ‘var’ referenced before assignment

***You can also use a global statement to create lazy global names by declaring them inside a function. Take a look at the following code:***
```python
def create_lazy_name():
    global lazy  # Create a global name, lazy
    lazy = 100
    return lazy

create_lazy_name()
100
lazy  # The name is now available in the 
global scope
100

The nonlocal Statement

• when you access a enclosed name from a inner local scope you cant update it unless you declare it as nonlocal inside the inner function.

def func():
    var = 100  # A nonlocal variable
    def nested():
        nonlocal var  # Declare var as nonlocal
        var += 100

    nested()
    print(var)

func()

• if we try to use nonlocal in the global scope it will throw error

nonlocal my_var # Try to use nonlocal in the global scope File "<stdin>", line 1

• we cant use nonlocal to create lazy variables.