what is scope in python

Understanding Python Scope
In Python, the scope of a variable determines the portion of the program where you can access that specific variable. Not every variable can be accessed from any location in a program.

Local vs Global Variables in Python
Python supports two types of variables based on their scope:

• Global Variables: These are declared outside a function and can be accessed throughout the program.
• Local Variables: These are declared inside a function and can be accessed only within that function.

If you’re creating a variable inside a function, it’s local by default. However, if you need to access or modify a global variable from within a function, you must use the global keyword before the variable.

Python Scope Example:
Let’s delve into examples to understand the use of local and global variables better. Here’s an example where a local variable inside a function is not accessible, and hence the code will not work:

def f(x,y):
    print('You called f(x,y) with the value x = ' + str(x) + ' and y = ' + str(y))
    print('x * y = ' + str(x*y))
    z = 4 # z is local here, and is not accessible outside the function

z = 3
f(3,2)

In contrast, here’s how defining the variable within the function scope allows it to be used:

def f(x,y):
    z = 3
    print('You called f(x,y) with the value x = ' + str(x) + ' and y = ' + str(y))
    print('x * y = ' + str(x*y))
    print(z) # z is local and defined within the function

f(3,2)

Another example where all the required variables are passed as parameters to the function:

def f(x,y,z):
    return x+y+z # returns the sum as all variables are provided as arguments

result = f(3,2,1)
print(result)

Nested Functions and Variable Scope
It’s possible to call functions within functions. When doing so, you can also fetch the value of a variable from another function. Let’s explore this with an example:

def highFive():
    return 5

def f(x,y):
    z = highFive() # fetching value from the highFive function
    return x+y+z 

result = f(3,2)
print(result)

To summarize, if a variable is accessible throughout the entire code, it’s termed as a global variable. If its access is restricted to a particular portion (like within a function), it’s termed a local variable.

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