blob: 4aed7ad6531a28b312988ac0da241c6688d709f5 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
---
short-description: Disabling options
...
# Disabling parts of the build
*This feature is available since version 0.44.0.*
The following is a common fragment found in many projects:
```meson
dep = dependency('foo')
# In some different directory
lib = shared_library('mylib', 'mylib.c',
dependencies : dep)
# And Ãn a third directory
exe = executable('mytest', 'mytest.c',
link_with : lib)
test('mytest', exe)
```
This works fine but gets a bit inflexible when you want to make this
part of the build optional. Basically it reduces to adding `if/else`
statements around all target invocations. Meson provides a simpler way
of achieving the same with a disabler object.
A disabler object is created with the `disabler` function:
```meson
d = disabler()
```
The only thing you can do to a disabler object is to ask if it has
been found:
```meson
f = d.found() # returns false
```
Any other statement that uses a disabler object will immediately
return a disabler. For example assuming that `d` contains a disabler
object then
```meson
d2 = some_func(d) # value of d2 will be disabler
d3 = true or d2 # value of d3 will be true because of short-circuiting
d4 = false or d2 # value of d4 will be disabler
if d # neither branch is evaluated
```
Thus to disable every target that depends on the dependency given
above, you can do something like this:
```meson
if use_foo_feature
d = dependency('foo')
else
d = disabler()
endif
```
This concentrates the handling of this option in one place and other
build definition files do not need to be sprinkled with `if`
statements.
|
