Subpar alternative/comparison documentation

[Code0x58]

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

At a glance (using a sample pex from heron) both produce python zip files:

• the par shebang uses python whereas pex uses something like python2.7
• the par zip has 0 compression which makes the file human readable/search
• the pex has a .bootstrap/ (including bytecode cache) and PEX-INFO

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?

trees of examples

par-example
├── __main__.py
├── org_apache_heron
│   └── heron
│       ├── common
│       │   ├── __init__.py
│       │   └── tests
│       │       ├── __init__.py
│       │       └── python
│       │           ├── __init__.py
│       │           └── pex_loader
│       │               ├── __init__.py
│       │               └── testdata
│       │                   ├── __init__.py
│       │                   └── src
│       │                       ├── __init__.py
│       │                       ├── sample
│       │                       └── sample.py
│       └── __init__.py
└── subpar
    ├── __init__.py
    └── runtime
        ├── __init__.py
        └── support.py

10 directories, 13 files

pex-example
├── .bootstrap
│   ├── __init__.py
│   ├── _markerlib
│   │   ├── __init__.py
│   │   ├── __init__.pyc
│   │   ├── markers.py
│   │   └── markers.pyc
│   ├── _pex
│   │   ├── archiver.py
│   │   ├── archiver.pyc
│   │   ├── base.py
│   │   ├── base.pyc
│   │   ├── common.py
│   │   ├── common.pyc
│   │   ├── compatibility.py
│   │   ├── compatibility.pyc
│   │   ├── compiler.py
│   │   ├── compiler.pyc
│   │   ├── crawler.py
│   │   ├── crawler.pyc
│   │   ├── environment.py
│   │   ├── environment.pyc
│   │   ├── fetcher.py
│   │   ├── fetcher.pyc
│   │   ├── finders.py
│   │   ├── finders.pyc
│   │   ├── http.py
│   │   ├── http.pyc
│   │   ├── __init__.py
│   │   ├── __init__.pyc
│   │   ├── installer.py
│   │   ├── installer.pyc
│   │   ├── interpreter.py
│   │   ├── interpreter.pyc
│   │   ├── iterator.py
│   │   ├── iterator.pyc
│   │   ├── link.py
│   │   ├── link.pyc
│   │   ├── orderedset.py
│   │   ├── orderedset.pyc
│   │   ├── package.py
│   │   ├── package.pyc
│   │   ├── pep425.py
│   │   ├── pep425.pyc
│   │   ├── pex_bootstrapper.py
│   │   ├── pex_bootstrapper.pyc
│   │   ├── pex_builder.py
│   │   ├── pex_builder.pyc
│   │   ├── pex_info.py
│   │   ├── pex_info.pyc
│   │   ├── pex.py
│   │   ├── pex.pyc
│   │   ├── platforms.py
│   │   ├── platforms.pyc
│   │   ├── requirements.py
│   │   ├── requirements.pyc
│   │   ├── resolvable.py
│   │   ├── resolvable.pyc
│   │   ├── resolver_options.py
│   │   ├── resolver_options.pyc
│   │   ├── resolver.py
│   │   ├── resolver.pyc
│   │   ├── sorter.py
│   │   ├── sorter.pyc
│   │   ├── testing.py
│   │   ├── testing.pyc
│   │   ├── tracer.py
│   │   ├── tracer.pyc
│   │   ├── translator.py
│   │   ├── translator.pyc
│   │   ├── util.py
│   │   ├── util.pyc
│   │   ├── variables.py
│   │   ├── variables.pyc
│   │   ├── version.py
│   │   └── version.pyc
│   ├── pkg_resources
│   │   ├── __init__.py
│   │   ├── __init__.pyc
│   │   └── _vendor
│   │       ├── __init__.py
│   │       ├── __init__.pyc
│   │       └── packaging
│   │           ├── __about__.py
│   │           ├── __about__.pyc
│   │           ├── _compat.py
│   │           ├── _compat.pyc
│   │           ├── __init__.py
│   │           ├── __init__.pyc
│   │           ├── specifiers.py
│   │           ├── specifiers.pyc
│   │           ├── _structures.py
│   │           ├── _structures.pyc
│   │           ├── version.py
│   │           └── version.pyc
│   ├── pkg_resources.py
│   └── pkg_resources.pyc
├── heron
│   ├── common
│   │   ├── __init__.py
│   │   └── tests
│   │       ├── __init__.py
│   │       └── python
│   │           ├── __init__.py
│   │           └── pex_loader
│   │               ├── __init__.py
│   │               └── testdata
│   │                   ├── __init__.py
│   │                   └── src
│   │                       ├── __init__.py
│   │                       ├── sample.py
│   │                       └── sample.pyc
│   └── __init__.py
├── __main__.py
├── __main__.pyc
└── PEX-INFO

13 directories, 103 files

[jsirois]

It would be excellent if you closed either pex-tool/pex#636 or this issue to keep a single stream of conversation going. That said - there is more detail here. I can say the shebang in pex is configurable. Installing pex and executing pex --help will be instructive as will it's docs ; a good entrypoint for those is at https://github.com/pantsbuild/pex/blob/master/README.rst.

There are differences between pex, and the pexes pants creates. Pants does not expose every option pex supports today - and it may make sense to expose more (Pants feature requests are appropriate here), or it may be a Pants bug when certain options aren't used or used properly (your interpreter constraints or python target cmpatibilities allow for python3 but the generated pex shebang is python2).