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python-build-standalone has exploded in popularity, with over 70M downloads all-time. But what is a "standalone" Python build? It wasn't obvious to me at first! Initially, I didn't understand what problem was being solved or why it mattered...

First, some context on the problem. Normally, when you build CPython on Linux or macOS, several system paths are hardcoded into the binary.

Normally, CPython is also dynamically linked against a number of system libraries, which can cause trouble if the target machine doesn't have those libraries installed.

In this way, CPython is not "standalone": it's tightly coupled to the system on which it was built (at least on Linux and macOS).

So, when you download Python from python.org on Linux, what you're actually downloading is an installer that builds Python from source on your machine. Similarly, when you install Python with pyenv, it too is building from source.

Which reminds me of my main problem with standalone builds on macOS: I can’t compile wheels because they assume some super weird Xcode path. I think it’s fair to say they can’t go full mainstream with that limitation so I wonder if that’s solvable at all? :-/

What’s this? I don’t have this problem and I build wheels all the time. Is there an issue somewhere?

yes, mortals like myself have Xcode at /Applications/Xcode.app but standalone expects it at /Applications/Xcode_15.2.app "Compiling with an SDK that doesn't seem to exist: /Applications/Xcode_15.2.app/..." Here's the example I could come up with fastest.