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.
You can now pass a list of strings to the install_dir: kwarg to
build_target and custom_target.
Custom Targets:
===============
Allows you to specify the installation directory for each
corresponding output. For example:
custom_target('different-install-dirs',
output : ['first.file', 'second.file'],
...
install : true,
install_dir : ['somedir', 'otherdir])
This would install first.file to somedir and second.file to otherdir.
If only one install_dir is provided, all outputs are installed there
(same behaviour as before).
To only install some outputs, pass `false` for the outputs that you
don't want installed. For example:
custom_target('only-install-second',
output : ['first.file', 'second.file'],
...
install : true,
install_dir : [false, 'otherdir])
This would install second.file to otherdir and not install first.file.
Build Targets:
==============
With build_target() (which includes executable(), library(), etc),
usually there is only one primary output. However some types of
targets have multiple outputs.
For example, while generating Vala libraries, valac also generates
a header and a .vapi file both of which often need to be installed.
This allows you to specify installation directories for those too.
# This will only install the library (same as before)
shared_library('somevalalib', 'somesource.vala',
...
install : true)
# This will install the library, the header, and the vapi into the
# respective directories
shared_library('somevalalib', 'somesource.vala',
...
install : true,
install_dir : ['libdir', 'incdir', 'vapidir'])
# This will install the library into the default libdir and
# everything else into the specified directories
shared_library('somevalalib', 'somesource.vala',
...
install : true,
install_dir : [true, 'incdir', 'vapidir'])
# This will NOT install the library, and will install everything
# else into the specified directories
shared_library('somevalalib', 'somesource.vala',
...
install : true,
install_dir : [false, 'incdir', 'vapidir'])
true/false can also be used for secondary outputs in the same way.
Valac can also generate a GIR file for libraries when the `vala_gir:`
keyword argument is passed to library(). In that case, `install_dir:`
must be given a list with four elements, one for each output.
Includes tests for all these.
Closes https://github.com/mesonbuild/meson/issues/705
Closes https://github.com/mesonbuild/meson/issues/891
Closes https://github.com/mesonbuild/meson/issues/892
Closes https://github.com/mesonbuild/meson/issues/1178
Closes https://github.com/mesonbuild/meson/issues/1193
This avoids unnecessary rebuilds occuring when Meson regenerates the
build.ninja file. Previously, if the ordering of the commandline
arguments changed then Ninja would consider the outputs dirty and
rebuild them.
There is no need to do obj.get_command() and in fact it's wrong
because the VS backends need to resolve each object to absolute paths
and get_command() does not do that.
This should fix invocation of GNOME module helpers with the VS backends
For the record, absolute paths for programs are needed because the
same PATH environment won't necessarily be available to Visual Studio
when it builds the generated solution.
Related to https://github.com/mesonbuild/meson/issues/1419
This used to produce a warning, but then would crash anyway. It's
simpler if we just error out and have the user disable gir generation or
install gobject-introspection.
We can't support generated XML files with custom_target() because the
dependency scanning happens at configure time, but we *can* support
generating them with configure_file().
Closes https://github.com/mesonbuild/meson/issues/1380
We don't need dependencies to work correctly to use the output of
configure_file in the dependencies: kwarg.
This allows GNOME Recipes to built without the latest glib git.
Cache the absolute dir that the script is searched in and the name of
the script. These are the only two things that change.
Update the test to test for both #1235 and the case when a script of the
same name is in a different directory (which also covers the subproject
case).
Closes#1235
Also don't use `dependencies` as a module name since it is commonly used
as a variable name too. Instead, directly import the classes that we use
from that module.
This avoids printing several 'Found:' messages during configure, and
also avoids doing several searches for the same binary. This is already
done by the interpreter for `find_program` calls from build files.
Also move it to the module-wide __init__.py file so it can be used by
other modules as-needed.
Also use it for g-ir-scanner where it was missed in one place, also fix
exception name in the same place.
It is often useful to be able to check if a specific object is of a type
defined in a module. To that end, define all such targets in
modules/__init__.py so that everyone can refer to them without poking
into module-specific code.
Without this, the user has to both compile the resource with
gnome.compile_resources, pass that to the target sources, and also
pass --gresources=/path/to/gres.xml to vala_args in the target.
With this, we will do that automatically.
Everywhere we use this object, we end up iterating over it and comparing
compiler.get_language() with something. Using a dict is the obvious
choice and simplifies a lot of code.
Instead of adding it everywhere manually, create a wrapper called
mesonlib.Popen_safe and use that everywhere that we call an executable
and extract its output.
This will also allow us to tweak it to do more/different things if
needed for some locales and/or systems.
Closes#1079
Dylan Baker