This allows a CustomTarget to be indexed, and the resulting indexed
value (a CustomTargetIndex type), to be used as a source in other
targets. This will confer a dependency on the original target, but only
inserts the source file returning by index the original target's
outputs. This can allow a CustomTarget that creates both a header and a
code file to have it's outputs split, for example.
Fixes#1470
I got this warning on a build:
> WARNING: Passed invalid keyword argument preset. This will become a hard error in the future.
I had to grep in meson code to understand that "preset" was the name of
the invalid argument. This is not obvious at all depending on the
argument name (here it looked like it was about argument presets).
Let's make it clearer by putting it in quotes.
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.
To reproduce, one could write:
foo = files('foo.c')
foo[0].path()
and get:
Traceback (most recent call last):
[snip]
File "/home/trhd/Projects/meson/mesonbuild/interpreterbase.py", line 398, in method_call
raise InvalidArguments('Variable "%s" is not callable.' % object_name)
UnboundLocalError: local variable 'object_name' referenced before assignment
Fix this by handling file objects separately.
Dylan Baker
Nirbheek Chauhan
Jussi Pakkanen
Jehan
Elliott Sales de Andrade
Hemmo Nieminen
Mike Sinkovsky
Igor Gnatenko