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138 lines
3.8 KiB
ReStructuredText
138 lines
3.8 KiB
ReStructuredText
.. _mach_settings:
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========
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Settings
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========
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Mach can read settings in from a set of configuration files. These
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configuration files are either named ``machrc`` or ``.machrc`` and
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are specified by the bootstrap script. In mozilla-central, these files
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can live in ``~/.mozbuild`` and/or ``topsrcdir``.
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Settings can be specified anywhere, and used both by mach core or
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individual commands.
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Core Settings
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=============
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These settings are implemented by mach core.
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* alias - Create a command alias. This is useful if you want to alias a command to something else, optionally including some defaults. It can either be used to create an entire new command, or provide defaults for an existing one. For example:
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.. parsed-literal::
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[alias]
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mochitest = mochitest -f browser
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browser-test = mochitest -f browser
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Defining Settings
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=================
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Settings need to be explicitly defined, along with their type,
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otherwise mach will throw when trying to access them.
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To define settings, use the :func:`~decorators.SettingsProvider`
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decorator in an existing mach command module. E.g:
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.. code-block:: python
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from mach.decorators import SettingsProvider
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from mozbuild.base import MachCommandBase
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@SettingsProvider
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class ArbitraryClassName(MachCommandBase):
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config_settings = [
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('foo.bar', 'string', "A helpful description"),
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('foo.baz', 'int', "Another description", 0, {'choices': set([0,1,2])}),
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]
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``@SettingsProvider``'s must specify a variable called ``config_settings``
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that returns a list of tuples. Alternatively, it can specify a function
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called ``config_settings`` that returns a list of tuples.
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Each tuple is of the form:
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.. code-block:: python
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('<section>.<option>', '<type>', '<description>', default, extra)
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``type`` is a string and can be one of:
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string, boolean, int, pos_int, path
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``description`` is a string explaining how to define the settings and
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where they get used. Descriptions should ideally be multi-line paragraphs
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where the first line acts as a short description.
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``default`` is optional, and provides a default value in case none was
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specified by any of the configuration files.
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``extra`` is also optional and is a dict containing additional key/value
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pairs to add to the setting's metadata. The following keys may be specified
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in the ``extra`` dict:
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* ``choices`` - A set of allowed values for the setting.
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Wildcards
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---------
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Sometimes a section should allow arbitrarily defined options from the user, such
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as the ``alias`` section mentioned above. To define a section like this, use ``*``
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as the option name. For example:
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.. parsed-literal::
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('foo.*', 'string', 'desc')
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This allows configuration files like this:
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.. parsed-literal::
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[foo]
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arbitrary1 = some string
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arbitrary2 = some other string
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Finding Settings
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================
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You can see which settings are available as well as their description and
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expected values by running:
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.. parsed-literal::
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./mach settings # or
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./mach settings --list
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Accessing Settings
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==================
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Now that the settings are defined and documented, they're accessible from
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individual mach commands from the mach command context.
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For example:
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.. code-block:: python
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from mach.decorators import (
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Command,
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SettingsProvider,
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)
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from mozbuild.base import MachCommandBase
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@SettingsProvider
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class ExampleSettings(object):
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config_settings = [
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('a.b', 'string', 'desc', 'default'),
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('foo.bar', 'string', 'desc',),
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('foo.baz', 'int', 'desc', 0, {'choices': set([0,1,2])}),
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]
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@Command('command', category='misc',
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description='Prints a setting')
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def command(command_context):
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settings = command_context._mach_context.settings
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print(settings.a.b)
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for option in settings.foo:
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print(settings.foo[option])
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