Python Namespace

A namespace is a system that organizes names (i.e., identifiers) in a way that they can be assigned to objects and easily accessed during the execution of a program. It helps in avoiding naming conflicts and provides a hierarchical structure for names to be stored and referenced.

Python has different types of namespaces, which include:

1. Built-in Namespace: It contains all the names of Python's built-in functions, modules, and exceptions. These names are always available without any import statement. For example, print(), len(), range(), etc.

2. Global Namespace: It represents the names defined at the top level of a module or script. These names can be accessed from anywhere within the module.

3. Enclosing Namespace: This namespace comes into play when working with nested functions. It contains the names from the nearest enclosing function.

4. Local Namespace: It includes the names defined within the current function or block. These names are created when a function is called and removed when the function exits.

When a name is accessed, Python searches for it in the following order:

1. Local Namespace (if the code is inside a function or block)

2. Enclosing Namespace (if the code is inside a nested function)

3. Global Namespace (for names defined at the top level of the module)

4. Built-in Namespace

If a name is found in any of these namespaces, Python retrieves its value. If not found, it raises a NameError.

Example:

# Global Namespace

global_var = 10

def my_function():

    # Local Namespace

    local_var = 20

    print(global_var)  # Accessing global_var from the Global Namespace

    def nested_function():

        # Enclosing Namespace

        enclosing_var = 30

        print(local_var)  # Accessing local_var from the Local Namespace

    nested_function()

my_function()

In this example, global_var is defined in the Global Namespace and is accessible within the function my_function. local_var is defined in the Local Namespace of my_function and is accessible within the function and its nested function nested_function.