meson: simplify lookup of python command

[apprehensions]

No description provided.

[kjellahl]

According to the commit message of 82005b8
it's wise to get the python installation with import('python').find_installation(),
to be sure to use the python version that Meson uses.
I don't use Visual Studio myself. I'm not sure what problems may occur with
find_program('python3', version: '>=3.5'). I'd prefer to stick to
import('python').find_installation(). But the version test is unnecessary.
It can be removed. Meson itself requires python3 >= 3.7.
See https://mesonbuild.com/Getting-meson.html.

[apprehensions]

I'm not sure what problems may occur with

They solve problems with other meson specification implementations.

But the version test is unnecessary.

libsigcplusplus/meson.build

Lines 44 to 50 in b8260dd

	python3 = import('python').find_installation()
	python_version = python3.language_version()
	python_version_req = '>= 3.5'
	if not python_version.version_compare(python_version_req)
	error('Requires Python @0@, found @1@.'.format(python_version_req, python_version))
	endif

So is this complex lookup of the version - which looks for '3.5', hence why its added.

[kjellahl]

@fanc999 Do you think it's safe to change

python3 = import('python').find_installation()

to

python3 = find_program('python3', version: '>=3.5')

wael thinks import('python').find_installation() is unnecessarily complex.

@wael444 I wonder if you misunderstood my But the version test is unnecessary.
I meant the 5-line test in meson.build just now.

[eli-schwartz]

The purpose of the python module's find_installation method is to provide a rich object with methods for building python extensions.

If you just need a script interpreter, and stick to the stdlib so you don't need to use the modules: kwarg, then find_program() is indeed simpler -- and will fall back to using the python that Meson itself uses.

[fanc999]

Hi @kjellahl ,

I think it might be ok, but I don't think it's really necessary. We could just take out the version check below, since Meson 0.55.x+ already requires Python 3.5.x or later.

With blessings, and cheers!

[kjellahl]

I've merged this PR and copied the commit to the libsigc++-2-12 branch.