Subpar alternative/comparison documentation

[Code0x58]

copied over from issue on website repo pantsbuild/pantsbuild.github.io/issues/10 for exposure

The PEX Design page doesn't list subpar as an alternative, although it seems to be.

I don't know how much is configurable between the two, or how different situations are handled (such as C extensions). It looks like pex isn't very portable, but handles dependencies at least a bit differently.

Does anyone know the two well enough to be able to give a fairly detailed comparison on the practical differences in the website repo?

[jsirois]

The PEX Design page doesn't list subpar as an alternative, although it seems to be.

PEX was designed in 2010 and 1st open sourced in 2011; so subpar was not an alternative at the time [1]. PARs were still a Google internal-only thing at that point; although they were known and served as inspiration with the key difference that Google controlled their underlying OS and so could more easily package an interpreter into the archive. Out here in the wild west, this is trickier since we'd need to be able to package up an interpreter for OSX, various linuces and - someday - windows. As such a specific non-goal of pex was tackling embedding an interpreter. Instead, pex tries to support interpreter constraints via various means so the "right" interpreter is picked from the host environment. Additionally, pex has supported multi-platform pexes from ~day one. The idea here is native deps for multiple platforms are embedded in a single pex. This primarily allowed building a pex on, say a linux CI machine, but having the resulting binary work on linux and OSX. I know ~nothing about subpar so can't say much more.

[1] google/subpar@e1f097e

[jsirois]

I'm re-opening since #2096 is about to ship and I'll let the PR closing that issue close this as well for better cross-reference.

[jsirois]

With the release of Pex 2.11.0, you can now add --par {eager,lazy} to your Pex command line and get a PEX with interpreter included.