Local scope in Python - Step-by-Step Execution

Concept Flow - Local scope

Start function

↓

Create local variables

↓

Use local variables

↓

Function ends

↓

Local variables destroyed

When a function runs, it creates its own local variables that exist only inside it. After the function finishes, these variables disappear.

Execution Sample

Python

def greet():
    message = "Hello"
    print(message)

greet()

This code defines a function with a local variable and prints it when the function is called.

Execution Table

Step	Action	Local Variables	Output
1	Function greet() is called	message: undefined
2	Local variable message created with value 'Hello'	message: 'Hello'
3	print(message) outputs message	message: 'Hello'	Hello
4	Function greet() ends, local variables destroyed	message: destroyed

💡 Function ends, local variable 'message' no longer exists

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
message	undefined	'Hello'	'Hello'	destroyed

Key Moments - 2 Insights

Why can't we use the variable 'message' outside the function?

Because 'message' is local to the function as shown in step 4 of the execution_table, it is destroyed when the function ends and does not exist outside.

What happens if we try to print 'message' before it is created inside the function?

The variable 'message' is undefined before step 2, so trying to use it before creation would cause an error.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'message' at Step 3?

A undefined

B 'Hello'

C destroyed

D None

💡 Hint

Check the 'Local Variables' column at Step 3 in the execution_table.

At which step does the local variable 'message' get destroyed?

A Step 2

B Step 3

C Step 4

D Never destroyed

💡 Hint

Look at the 'Action' column in the execution_table describing function end.

If we try to print 'message' outside the function, what will happen?

A It will cause an error

B It will print None

C It will print 'Hello'

D It will print an empty string

💡 Hint

Refer to the key_moments explanation about variable scope and destruction.

Concept Snapshot

Local scope means variables created inside a function exist only there.
They are created when the function runs and destroyed when it ends.
You cannot use local variables outside their function.
Trying to access them outside causes an error.

Full Transcript

Local scope means variables defined inside a function are only available inside that function. When the function starts, local variables are created. When the function ends, these variables are destroyed and no longer exist. For example, in the code, the variable 'message' is created inside the function greet and printed. After greet finishes, 'message' is destroyed. If you try to use 'message' outside greet, it will cause an error because it does not exist there.