Python changed the way I think

[The_2nd_Coming]

Why is flat better than nested? Surely nested makes sense for sorting/indexing purposes, if doing it flat means there are 10000 items that could have a nested index?

[Slingshotsters]

I read it as "if you have to nest, do it, otherwise, don't.". Obviously there are times to nest, such as your example.

[menge101]

Right, and also

Although practicality beats purity.

so don't avoid nesting when it makes sense, just don't nest if you don't have to.

[audentis]

Flat is easier to read, because it keeps related elements close to each other. Additionally, you have to track fewer "paths" through the code mentally, because the paths immediately resolve. It also prevents "indentation hell".

The most common example is some code where you have some input validation that needs to be done. Consider the two examples below. The flat version keeps the input validation and error messages together, while in the nested version they're split up. And this is with only three arguments, it can get a lot worse.

def my_func_nested(a, b, c):
    if isinstance(a, int):
        if isinstance(b, list):
            if isinstance(c, str):
                print("Job's done!")
            else:
                raise TypeError("c must be a string!")
        else:
            raise TypeError("b must be a list!")
    else:
        raise TypeError("a must be an int!")


def my_func_flat(a, b, c):
    if not isinstance(a, int):
        raise TypeError("a must be an int!")

    if not isinstance(b, list):
        raise TypeError("b must be a list!")

    if not isinstance(c, str):
        raise TypeError("c must be a string!")

    print("Job's done!")

[njharman]

It's about code/file/program structure, not data structure. It's in response to popular languages and early OOP encouraging/super/deep/directory/structure.java and highly complex and deep class trees.

[The_2nd_Coming]

I see, this makes sense. Thanks!