Meson has a common pattern of using 'if len(foo) == 0:' or
'if len(foo) != 0:', however, this is a common anti-pattern in python.
Instead tests for emptiness/non-emptiness should be done with a simple
'if foo:' or 'if not foo:'
Consider the following:
>>> import timeit
>>> timeit.timeit('if len([]) == 0: pass')
0.10730923599840025
>>> timeit.timeit('if not []: pass')
0.030033907998586074
>>> timeit.timeit('if len(['a', 'b', 'c', 'd']) == 0: pass')
0.1154778649979562
>>> timeit.timeit("if not ['a', 'b', 'c', 'd']: pass")
0.08259823200205574
>>> timeit.timeit('if len("") == 0: pass')
0.089759664999292
>>> timeit.timeit('if not "": pass')
0.02340641999762738
>>> timeit.timeit('if len("foo") == 0: pass')
0.08848102600313723
>>> timeit.timeit('if not "foo": pass')
0.04032287199879647
And for the one additional case of 'if len(foo.strip()) == 0', which can
be replaced with 'if not foo.isspace()'
>>> timeit.timeit('if len(" ".strip()) == 0: pass')
0.15294511600222904
>>> timeit.timeit('if " ".isspace(): pass')
0.09413968399894657
>>> timeit.timeit('if len(" abc".strip()) == 0: pass')
0.2023209120015963
>>> timeit.timeit('if " abc".isspace(): pass')
0.09571301700270851
In other words, it's always a win to not use len(), when you don't
actually want to check the length.
Using Meson from outside a git repo results in an error when trying to
resolve submodule subprojects. Running git from inside subproject root
should be enough to fix it.
Partially fixes#1679
Signed-off-by: Ernestas Kulik <ernestas.kulik@gmail.com>
After an initial checkout, submodules aren’t initialized and thus trying
to update them fails.
Partially fixes#1679
Signed-off-by: Ernestas Kulik <ernestas.kulik@gmail.com>
Special wrap modes:
nofallback: Don't download wraps for dependency() fallbacks
nodownload: Don't download wraps for all subproject() calls
Subprojects are used for two purposes:
1. To download and build dependencies by using .wrap files if they
are not provided by the system. This is usually expressed via
dependency(..., fallback: ...).
2. To download and build 'copylibs' which are meant to be used by
copying into your project. This is always done with an explicit
subproject() call.
--wrap-mode=nofallback will never do (1)
--wrap-mode=nodownload will do neither (1) nor (2)
If you are building from a release tarball, you should be able to
safely use 'nodownload' since upstream is expected to ship all
required sources with the tarball.
If you are building from a git repository, you will want to use
'nofallback' so that any 'copylib' wraps will be download as
subprojects.
Note that these options do not affect subprojects that are git
submodules since those are only usable in git repositories, and you
almost always want to download them.
This will benefit projects such as GNOME Recipes that prefer using
submodules over wraps because it's easier to maintain since git is
aware of it, and because it integrates with their existing
workflow. Without this, these projects have to manually initialize
the submodules which is completely unnecessary.
Closes https://github.com/mesonbuild/meson/issues/1449
Also use a pathlib.Path object for the checks since it does I/O only
once and is much more efficient anyway. Path objects are available
since Python 3.4, so this is fine.
Also did a bit of cleanup.
interpreter.py: There’s a catch all except clause at the line 1928, it didn’t give the user any information whatsoever about the exception it caught. Now it at least print it to the log as a warning.
* add support for wrap of mercurial repo, and a test with a clone of the sample subproject used for the git test into a mercuriel repo.
* Added myself to author list, and switched the URL of the sample subproject in the wrap file to one under the control of the project's maintainers.
Alistair Thomas
Goncalo Carvalho
Elliott Sales de Andrade
Dylan Baker
Ernestas Kulik
Nirbheek Chauhan
Marc Becker
Mike Sinkovsky
Igor Gnatenko
Jussi Pakkanen
Alexandre Foley
Thibault Saunier
Thibault Saunier