Python Namespace

Learn Python Programming Language Python Namespace

In this lesson, you will learn about the namespace, the mapping of names to objects, and the scope of a variable, with examples to better understand the topic.

Namespaces are one excellent concept — let’s do more of those; the final line reads in “The Zen of Python” (type import this in the Python interpreter). So what exactly are these enigmatic namespaces? Let’s start by examining what the name is.

What is a Namespace?

Python treats everything as an object. All an object has is its name, often known as an identifier, and the underlying object can be accessed using its name. So, a namespace is a collection of currently defined symbolic names and details about the objects to which each name refers. You can compare a namespace to a dictionary where the keys are the names of the things, and the values are the actual objects.

Through the built-in function id, we may obtain the address (in RAM) of some object (). For instance, when we perform the assignment, mathMarks = 99, the name we give it to, and 99 is an object stored in memory. Let’s examine its application.

Example

mathMarks = 1
print('id(mathMarks) =', id(mathMarks))
mathMarks = mathMarks+1
print('id(mathMarks) =', id(mathMarks))
print('id(3) =', id(3))
engmarks = 2
print('id(engmarks) =', id(engmarks))
print('id(2) =', id(2))

Output

id(mathMarks) = 9788992
id(mathMarks) = 9789024
id(3) = 9789056
id(engmarks) = 9789024
id(2) = 9789024

As you can see in the above example, you may get different values for the id.

When we do mathMarks = mathMarks + 1, a new object 3 is formed, and now the name is associated with this object. Initially, object 2 is generated, and the name is associated with it. Note that the values of id(mathMarks) and id(3) are identical.

Furthermore, the new name engmarks is connected to the prior object 2 when engmarks = 2 is executed. Because Python doesn’t have to construct a new duplicate object, this is efficient. Python is strong because of the dynamic nature of name binding, which allows names to refer to any object.

i = 500
i = 'Hello World!'
i = [100,200,300]

All these are acceptable, and a will, in various contexts, refers to three distinct categories of objects. Since functions are objects, their names are used to identify them.

def mathMarks():
print("100")
m = mathMarks
m()

Output

What exactly is a Python namespace?

We can discuss namespaces now that we are familiar with the definition of names.

A namespace is, to put it simply, a collection of names.
A namespace in Python is a mapping between each name you’ve created and the accompanying objects.
At any given time, various namespaces can coexist but are segregated.
When we launch the Python interpreter, a namespace containing all the built-in names is produced and exists as long as the interpreter is active.
Because of this, we always have access to built-in functions like id(), print(), and others from any portion of the program. Every module establishes its global namespace.
These several namespaces exist in isolation. As a result, names that may be the same yet appear in various modules do not overlap.
Different types and functions are possible for modules. When a function is invoked, a local namespace is formed with all the names defined in it. The same is true of class. The diagram that follows might make this idea clearer.

Python Variable Scope

Although many distinct namespaces have been declared, not all of them may be accessible from every part of the program. The idea of scope is involved, and you can access a namespace straight from a program’s scope without needing a prefix in Python.

In Python, at least three nested scopes are always active.

Scope of the current function’s domain, which has local names
Scope of the module’s domain, which contains global names
Outermost scope with names already built-in

A name is first searched in the local namespace, then in the global namespace, and finally in the built-in namespace when a reference is made inside a function. A new scope is nested inside the local scope if a function is contained within another.

Example

def outer_function():
hisMarks = 80
def inner_function():
engMarks = 90
mathMarks =100

The variable mathMarks in this instance, is in the global namespace. The outer function(local )’s namespace contains the variable hisMarks, and the inner function’s nested local namespace contains the variable engMarks().

mathMarks is global, hisMarks is nonlocal, and engMarks is local to us when we are in inner function(). We can read from the inner function and add new values to engMarks, but we can only read from it engMarks and mathMarks().

A new variable name hisMarks is created in the local namespace when we attempt to assign the mathMarks value to the nonlocal variable engMarks. When we give a value, the same thing occurs.

However, we receive all references and assignments if we designate them as global. Similarly, the variable hisMarks must be marked as nonlocal if we want to rebind it. The below given an example will make this clear.

Example

def outer_function():
mathMarks = 80
def inner_function():
mathMarks = 90
print('mathMarks =', mathMarks)
inner_function()
print('mathMarks =', mathMarks)
mathMarks = 100
outer_function()
print('mathMarks =', mathMarks)

Output

mathMarks = 90
mathMarks = 80
mathMarks = 100

This concludes the Python Namespace lesson. In the next lesson, you will learn about IO and import in Python and their usage.

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