[Python-ideas] CPython needs to revamp/replace it's build system && Cross-compiling Python sucks

[Brett Cannon]

On Tue, Mar 10, 2015 at 11:40 AM Ryan Gonzalez <rymg19 at gmail.com> wrote:

> On Tue, Mar 10, 2015 at 8:43 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:
>
>> On 10 March 2015 at 21:20, Russell Keith-Magee <russell at keith-magee.com>
>> wrote:
>> >
>> > On Tue, Mar 10, 2015 at 10:43 AM, Ryan <rymg19 at gmail.com> wrote:
>> >>
>> >> Russell Keith-Magee <russell at keith-magee.com> wrote:
>> >> >Hi Ryan,
>> >> >
>> >> >First off I'm no fan of autoconf, but...
>> >> >
>> >>
>> >> Who is other than the one who designed it? :)
>> >
>> > Let me be clear - there's a difference between "not a fan" and "calling
>> for
>> > it's head". Autoconf is crufty, annoying, and sometimes aggravating -
>> but it
>> > *works*, and has had some pretty seriously battle testing - both in the
>> > abstract "autoconf as a product", and in the specific "autoconf as used
>> in
>> > Python". This isn't something that can be said of most of the
>> alternatives
>> > in the abstract case, or *any* of the alternatives in the Python case.
>>
>> Building architecture dependent software is a genuinely hard problem,
>> which is why it's full of "80%" solutions like autotools and the
>> setuptools/distutils pairing. Yes, they're quirky and annoying, but
>> they also basically do their job, so folks tend to develop a high
>> tolerance level for their quirks.
>>
>> In our particular case, we also have the fun problem of "How do you
>> build CPython locally when you don't have a working Python interpreter
>> yet?". A number of the more interesting alternative C/C++ build
>> systems (like Meson, Scons, Waf and the Google "gyp" project that
>> powers the node-gyp native extension build system for Node.js) require
>> an already working Python interpreter to get things started (when
>> starting from a completely blank slate, even our own build sequence
>> has to build a deliberately broken partial interpreter just to freeze
>> importlib._bootstrap before going on to build a properly configured
>> one that can actually import modules).
>>
>
> What about something like Google's new GN? It's designed to replace Gyp in
> building Chromium and is written in C++.
>
> I'm pretty sure using a build system written in Lua to build Python is
> kind of weird.
>


>
> With all that in mind...what exactly would be requirements that Python
> would need in an autotools replacement?
>

Can't require anything more than an ANSI C compiler basically. People run
Python in places where they don't have much more than gcc.


>
>
>>
>> CMake seems like a plausible alternative that would avoid the
>> bootstrapping problem (as even building it from source only requires a
>> working C++ compiler for the platform, either native or
>> cross-compiled): http://www.cmake.org/
>>
>> KDE switched over to CMake from autotools ~9 years ago
>> (http://lwn.net/Articles/188693/) and plenty of other projects have
>> either followed suit or simply never used autotools in the first
>> place: http://www.cmake.org/Wiki/CMake_Projects
>>
>>
> That was what I was referring to before.
>

I casually discussed the idea back at PyCon 2008 about using CMake and was
told "no" because of potential build tool dependencies for CMake itself. So
you have to make sure that you can prove CMake is highly portable.


>
>
>> It's far too late in the 3.5 dev cycle to contemplate a change like
>> that, but if anyone was looking for a potentially interesting side
>> project, seeing exactly what was involved in getting CPython to build
>> with CMake instead of autotools could be a worthwhile investigation:
>>
>> https://stackoverflow.com/questions/7132862/tutorial-for-converting-autotools-to-cmake
>>
>>
> Someone is maintaining a set of CMake build files for Python 2.7 somewhere.
>

That's fine, but obviously things have been tweaked since then and this
could only go into 3.x.

-Brett


>
>
>> Regards,
>> Nick.
>>
>> --
>> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
>>
>
>
>
> --
> Ryan
> If I were in a 10-story building glass-sided building and forced to write
> either Go or autotools scripts, I’d jump out a window.
> http://kirbyfan64.github.io/
>
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