Why Does `str = str(...)` Cause a TypeError in Python?

Redefining Built-ins: Understanding the TypeError in 'str = str(...)'

In Python, modifying built-in objects can lead to unexpected errors. Consider the following code:

def example(parameter):
    global str
    str = str(parameter)
    print(str)

example(1)
example(2)

Upon executing this code, you may encounter two different scenarios. The first call to example() succeeds, while the second call raises a TypeError. This is because the second assignment to str redefines its meaning.

The Role of str()

In Python, str() is the predefined function that converts an object to a string. Assigning str to a new value overwrites this built-in functionality. By declaring str as global, you're indicating that it should refer to a top-level variable outside the function.

Correcting the Code

To resolve the TypeError, you have two options:

1. Use a Custom Variable: Choose a different name for the local variable within the example() function. Avoid using reserved Python names like str.
2. Remove the global Statement: Delete the global statement before assigning a new value to str. This will prevent modifying the global str reference within your function.

Remember, modifying built-in objects can have unintended consequences. Stick to using local variables within functions to prevent conflicts with Python's default behavior.

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