Benefits of os.path.splitext over regular .split?

Question

In this other question, the votes clearly show that the os.path.splitext function is preferred over the simple .split('.')[-1] string manipulation. Does anyone have a moment to explain exactly why that is? Is it faster, or more accurate, or what? I'm willing to accept that there's something better about it, but I can't immediately see what it might be. Might importing a whole module to do this be overkill, at least in simple cases?

EDIT: The OS specificity is a big win that's not immediately obvious; but even I should've seen the "what if there isn't a dot" case! And thanks to everybody for the general comments on library usage.

Answer 1

Well, there are separate implementations for separate operating systems. This means that if the logic to extract the extension of a file differs on Mac from that on Linux, this distinction will be handled by those things. I don't know of any such distinction so there might be none.

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Edit: @Brian comments that an example like /directory.ext/file would of course not work with a simple .split('.') call, and you would have to know both that directories can use extensions, as well as the fact that on some operating systems, forward slash is a valid directory separator.

This just emphasizes the use a library routine unless you have a good reason not to part of my answer.

Thanks @Brian.

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Additionally, where a file doesn't have an extension, you would have to build in logic to handle that case. And what if the thing you try to split is a directory name ending with a backslash? No filename nor an extension.

The rule should be that unless you have a specific reason not to use a library function that does what you want, use it. This will avoid you having to maintain and bugfix code others have perfectly good solutions to.

Answer 2

os.path.splitext will correctly handle the situation where the file has no extension and return an empty string. .split will return the name of the file.