Passing arguments to the PEP517 sipbuild.api backend

[Phil Thompson]

On 07/05/2022 12:37, Michał Górny wrote:
> On Sat, 2022-05-07 at 10:54 +0100, Phil Thompson wrote:
>> On 07/05/2022 10:33, Michał Górny wrote:
>> > On Sat, 2022-05-07 at 10:12 +0100, Phil Thompson wrote:
>> > > On 06/05/2022 14:51, Michał Górny wrote:
>> > > > Hello,
>> > > >
>> > > > I'm one of the maintainers of Python packages in Gentoo.  Lately we've
>> > > > been working on transitioning from the legacy "setup.py install"
>> > > > workflow to PEP517 build backends.  As part of that, I'd like to work
>> > > > on switching the packages relying on sip -- starting with recently
>> > > > released update to python-poppler-qt5 but eventually including PyQt.
>> > > >
>> > > > Unfortunately, I can't find a way to pass options to the PEP517 backend
>> > > > in the way that it is possible to the sip-build executable.  Is it
>> > > > possible to inject options currently?  If not, could you please add
>> > > > such
>> > > > a possibility?  The config_settings dictionary of build_wheel() method
>> > > > seems to be the usual method of doing that (cf. setuptools accepting
>> > > > {"--global_option": [...]}, though admittedly that double-dash is weird
>> > > > there).
>> > > >
>> > > > TIA.
>> > >
>> > > The sipbuild.api backend currently ignores any config settings because
>> > > (as it says in the comments) I wasn't aware of a frontend that seemed
>> > > to
>> > > support the feature so I couldn't test it properly.
>> > >
>> > > Do you have your own frontend or are you using pip (or similar)?
>> > >
>> >
>> > Yes-ish.  I've written gpep517 for our needs [1] but the more common
>> > build [2] package also supports passing config settings, e.g.:
>> >
>> >   gpep517 build-wheel --output-fd 1 --wheel-dir dist/ \
>> >     --config-json '{"--global-option": ["--foo"]}'
>> >
>> >   python -m build -nw --config-setting=--global-option=--foo
>> >
>> > [1] https://pypi.org/project/gpep517/
>> > [2] https://pypi.org/project/build/
>> 
>> So the config_settings argument passed to build_sdist() and
>> build_wheel() would be...
>> 
>> {'--global-option': '--foo'}
> 
> For build case, yes, this.  If I add a debug print into build_meta:
> 
>   {'--global-option': '--foo'}
> 
> However, if you pass multiple arguments with the same key, it turns 
> into
> a list, e.g.:
> 
>   $ python -m build -nw --config-setting=--global-option=--foo \
>       --config-setting=--global-option=--bar
> 
> yields:
> 
>   {'--global-option': ['--foo', '--bar']}
> 
> To account for this weird syntax, the setuptools backend checks
> if "--global-option" is a string, and converts it to list.
> 
> gpep517 passes the literal dict from unserialized JSON.
> 
> I'd imagine sipbuild would need to use a similar logic, i.e. something
> like:
> 
>   args = config_settings.get("args", [])
>   if isinstance(args, str):
>     args = [args]
> 
> if you want to support build as it currently works.  Personally, I just
> need gpep517 support, so the hack wouldn't be necessary.

The next snapshot should allow you to do...

python -m build --config-setting=--qmake=/path/to/qmake

...etc etc

Phil