A great door for hackers TL;DR: Don't use metaprogramming. It is not that cool Problems Security Limited Control Solutions Use direct calls Wrap the execution in a primitive and controlled command Sanitize it Context Developers employ the eval() and exec() functions to evaluate arbitrary expressions from strings. They can be a powerful tool in certain contexts but come with several risks and problems, especially when used with untrusted input or where the code's behavior is not fully controlled or understood. Sample Code Wrong def calculate(mathOperand, firstArgument, secondArgument):
    return eval(f'{firstArgument} {mathOperand} {secondArgument}')

# Sample usage to multiply two numbers
result = calculate('*', 4, 6)

# Injection to remove all files
calculate('', "__import__('os').system('rm -rf *')",'')) Right def calculate(mathOperand, firstArgument, secondArgument):
    if mathOperand == '+':
        return firstArgument + secondArgument
    elif mathOperand == '-':
        return firstArgument - secondArgument
    elif mathOperand == '*':
        return firstArgument * secondArgument
    elif mathOperand == '/':
        if secondArgument != 0:
            return firstArgument / secondArgument
        else:
            return "Error: Division by zero"
    else:
        return "Error: Invalid operation - Do not hack!"
        
# This is a quick solution but another smell
# You should avoid this kind of switches and iterate to 
# a Polymorphic Hierarchy Detection Automatic You can search for eval() in the code Tags Metaprogramming Level Intermediate AI Assistants Most AI Assistants avoid using eval() in their solutions. They also recognize it as a code smell and offer different options Conclusion Avoid this metaprogramming solution by hardcoding all the possible scenarios and avoiding over-generalizations. Relations Code Smell 207 - Dynamic Methods Code Smell 189 - Not Sanitized Input Code Smell 215 - Deserializing Object Vulnerability More Info https://hackernoon.com/laziness-chapter-i-meta-programming-6s4l300e?embedable=true Disclaimer Code Smells are my . opinion Credits Photo by on Yang Unsplash When you actually sit down to write some code, you learn things that you didn’t get from thinking about them in modeling terms…there is a feedback process there that you can only really get at from executing some things and seeing what works. Martin Fowler https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true This article is part of the CodeSmell Series. https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-i-xqz3evd?embedable=true

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Code Smell 245 — Exec() and Eval()

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