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68 lines
1.6 KiB
68 lines
1.6 KiB
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short-description: Disabling options |
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# Disabling parts of the build |
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*This feature is available since version 0.44.0.* |
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The following is a common fragment found in many projects: |
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```meson |
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dep = dependency('foo') |
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# In some different directory |
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lib = shared_library('mylib', 'mylib.c', |
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dependencies : dep) |
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# And in a third directory |
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exe = executable('mytest', 'mytest.c', |
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link_with : lib) |
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test('mytest', exe) |
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``` |
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This works fine but gets a bit inflexible when you want to make this |
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part of the build optional. Basically it reduces to adding `if/else` |
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statements around all target invocations. Meson provides a simpler way |
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of achieving the same with a disabler object. |
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A disabler object is created with the `disabler` function: |
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```meson |
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d = disabler() |
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``` |
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The only thing you can do to a disabler object is to ask if it has |
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been found: |
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```meson |
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f = d.found() # returns false |
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``` |
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Any other statement that uses a disabler object will immediately |
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return a disabler. For example assuming that `d` contains a disabler |
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object then |
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```meson |
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d2 = some_func(d) # value of d2 will be disabler |
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d3 = true or d2 # value of d3 will be true because of short-circuiting |
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d4 = false or d2 # value of d4 will be disabler |
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if d # neither branch is evaluated |
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``` |
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Thus to disable every target that depends on the dependency given |
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above, you can do something like this: |
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```meson |
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if use_foo_feature |
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d = dependency('foo') |
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else |
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d = disabler() |
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endif |
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``` |
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This concentrates the handling of this option in one place and other |
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build definition files do not need to be sprinkled with `if` |
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statements.
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