Use exec() for Dynamic Code Generation in Python

Hi Pythonistas!

Today I’m sharing one of Python’s most powerful and potentially risky tools: exec().

While you should use it cautiously, exec() can help you dynamically generate and execute code at runtime

useful in advanced tools, meta-programming, and code automation.

What Is exec()?

exec() runs any string as Python code, including full statements like defining functions, classes, or control flow.

code = """
def greet(name):
    print(f"Hello, {name}!")
"""
exec(code)

greet("Harry Potter ")

Output

Hello, Harry Potter!

You just created a function on the fly!

Real-Life Use Case: Dynamic Function Builder

>>> def make_adder(n):
...     code = f"""
... def add_{n}(x):
...     return x + {n}
... """
...     exec(code, globals())
... 

>>> make_adder(5)
>>> add_5(10)
15
>>>

You’ve now generated a function named add_5 dynamically!

Warning: exec() Is Powerful and Dangerous

If you’re using user input, don’t trust it blindly:

user_code = input("Enter some Python code: ")

exec(user_code) # This can be dangerous

Instead, use this only when:

You trust the input
You’re writing internal tools
You need dynamic behavior that can’t be easily refactored

summary

exec() runs any Python code from a string
Great for code generation, advanced tools, and dynamic behavior
Avoid with untrusted input

In the upcoming for we will discuss some safer alternative for exec