530 lines
17 KiB
Text
530 lines
17 KiB
Text
.. default-role:: literal
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===============================
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Options handling basics
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===============================
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Tiramisu is made of almost three main objects :
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- :class:`tiramisu.config.Config` witch is the whole configuration entry point
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- :class:`tiramisu.option.Option` stands for the option types
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- :class:`tiramisu.option.OptionDescription` is the shema, the option's structure
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Accessing the `Option`'s
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-------------------------
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The `Config` object attribute access notation stands for the value of the
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configuration's `Option`. That is, the `Config`'s object attribute is the name
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of the `Option`, and the value is the value accessed by the `__getattr__`
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attribute access mechanism.
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If the attribute of the `Config` called by `__getattr__` has not been set before
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(by the classic `__setattr__` mechanism), the default value of the `Option`
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object is returned, and if no `Option` has been declared in the
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`OptionDescription` (that is the schema of the configuration), an
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`AttributeError` is raised.
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::
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>>> gcdummy = BoolOption('dummy', 'dummy', default=False)
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>>> gcdummy._name
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'dummy'
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>>> gcdummy.getdefault()
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False
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>>> descr = OptionDescription('tiramisu', '', [gcdummy])
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>>> cfg = Config(descr)
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>>> cfg.dummy
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False
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>>> cfg.dummy = True
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>>> cfg.dummy
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True
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>>> cfg.idontexist
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AttributeError: 'OptionDescription' object has no attribute 'idontexist'
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The `Option` objects (in this case the `BoolOption`), are organized into a tree
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into nested `OptionDescription` objects. Every option has a name, as does every
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option group. The parts of the full name of the option are separated by dots:
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e.g. ``cfg.optgroup.optname``.
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Let's make the protocol of accessing a config's attribute explicit
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(because explicit is better than implicit):
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1. If the option has not been declared, an `AttributeError` is raised,
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2. If an option is declared, but neither a value nor a default value has
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been set, the returned value is `None`,
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3. If an option is declared and a default value has been set, but no value
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has been set, the returned value is the default value of the option,
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4. If an option is declared, and a value has been set, the returned value is
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the value of the option.
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But there are special exceptions. We will see later on that an option can be a
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:term:`mandatory option`. A mandatory option is an option that must have a defined value.
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If no value have been set yet, the value is `None`.
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When the option is called to retrieve a value, an exception is raised.
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What if a value has been set and `None` is to be returned again ? Don't
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worry, an option value can be "reseted" with the help of the `option.Option.reset()`
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method.
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If you know the path:
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::
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>>> config.gc.dummy
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False
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Setting the values of the options
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----------------------------------------
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An important part of the setting of the configuration consists of setting the
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values of the configuration options. There are different ways of setting values,
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the first one is of course the `__setattr__` method
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::
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cfg.name = value
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And if you wanna come back to a default value, use the builtin `del()` function::
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del(cfg.name)
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.. module:: tiramisu.config
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.. _`tree`:
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The handling of options
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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The handling of options is split into two parts: the description of
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which options are available, what their possible values and defaults are
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and how they are organized into a tree. A specific choice of options is
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bundled into a configuration object which has a reference to its option
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description (and therefore makes sure that the configuration values
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adhere to the option description).
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Common manipulations
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------------------------
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Let's perform some common manipulation on some options:
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>>> from tiramisu.config import Config
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>>> from tiramisu.option import UnicodeOption, OptionDescription
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>>>
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>>> var1 = UnicodeOption('var1', 'first variable')
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>>> var2 = UnicodeOption('var2', '', u'value')
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>>>
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>>> od1 = OptionDescription('od1', 'first OD', [var1, var2])
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>>> rootod = OptionDescription('rootod', '', [od1])
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let's set somme access rules on the main namespace
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>>> c = Config(rootod)
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>>> c.read_write()
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let's travel the namespaces
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>>> print c
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[od1]
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>>> print c.od1
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var1 = None
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var2 = value
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>>> print c.od1.var1
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None
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>>> print c.od1.var2
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value
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let's modify a value (careful to the value's type...)
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>>> c.od1.var1 = 'value'
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Traceback (most recent call last):
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[...]
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ValueError: invalid value value for option var1
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>>> c.od1.var1 = u'value'
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>>> print c.od1.var1
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value
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>>> c.od1.var2 = u'value2'
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>>> print c.od1.var2
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value2
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let's come back to the default value
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>>> del(c.od1.var2)
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>>> print c.od1.var2
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value
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The value is saved in a :class:`~tiramisu.value.Value` object. It is on this
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object that we have to trigger the `reset`, wich take the option itself
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(`var2`) as a parameter.
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On the other side, in the `read_only` mode, it is not possible to modify the value::
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>>> c.read_only()
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>>> c.od1.var2 = u'value2'
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError:
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cannot change the value to var2
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for option ['frozen'] this option is frozen
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let's retrieve the option `var1` description
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>>> var1.impl_get_information('doc')
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'first variable'
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And if the option has been lost, it is possible to retrieve it again:
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>>> c.unwrap_from_path('od1.var1').impl_get_information('doc')
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'first variable'
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Searching for an option
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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In an application, knowing the path of an option is not always feasible.
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That's why a tree of options can easily be searched. First, let's build such a tree::
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>>> var1 = UnicodeOption('var1', '')
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>>> var2 = UnicodeOption('var2', '')
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>>> var3 = UnicodeOption('var3', '')
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>>> od1 = OptionDescription('od1', '', [var1, var2, var3])
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>>> var4 = UnicodeOption('var4', '')
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>>> var5 = UnicodeOption('var5', '')
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>>> var6 = UnicodeOption('var6', '')
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>>> var7 = UnicodeOption('var1', '', u'value')
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>>> od2 = OptionDescription('od2', '', [var4, var5, var6, var7])
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>>> rootod = OptionDescription('rootod', '', [od1, od2])
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>>> c = Config(rootod)
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>>> c.read_write()
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Second, let's find an option by his name::
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>>> print c.find(byname='var1')
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[<tiramisu.option.UnicodeOption object at 0x7ff1bf7d6ef0>,
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<tiramisu.option.UnicodeOption object at 0x7ff1b90c7290>]
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If the option name is unique, the search can be stopped once one matched option
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has been found:
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>>> print c.find_first(byname='var1')
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<tiramisu.option.UnicodeOption object at 0x7ff1bf7d6ef0>
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Instead of the option's object, the value or path can be retrieved:
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>>> print c.find(byname='var1', type_='value')
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[None, u'value']
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>>> print c.find(byname='var1', type_='path')
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['od1.var1', 'od2.var1']
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Finaly, a search can be performed on the values, the type or even a combination
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of all these criteria:
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>>> print c.find(byvalue=u'value', type_='path')
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['od2.var1']
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>>> print c.find(bytype=UnicodeOption, type_='path')
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['od1.var1', 'od1.var2', 'od1.var3', 'od2.var4', 'od2.var5', 'od2.var6', 'od2.var1']
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>>> print c.find(byvalue=u'value', byname='var1', bytype=UnicodeOption, type_='path')
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['od2.var1']
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The search can be performed in a subtree:
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>>> print c.od1.find(byname='var1', type_='path')
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['od1.var1']
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In a root tree or in a subtree, all option can be retrieved in a dict container:
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>>> print c.make_dict()
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{'od2.var4': None, 'od2.var5': None, 'od2.var6': None, 'od2.var1': u'value',
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'od1.var1': None, 'od1.var3': None, 'od1.var2': None}
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If the organisation in a tree is not important,
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:meth:`~config.SubConfig.make_dict()` results can be flattened
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>>> print c.make_dict(flatten=True)
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{'var5': None, 'var4': None, 'var6': None, 'var1': u'value', 'var3': None,
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'var2': None}
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.. note:: carefull with this `flatten` parameter, here we have just lost
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two options named `var1`
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One can export only interesting parts of a tree of options into a dict, for
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example the options that are in the same group that a given `var1` option::
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>>> print c.make_dict(withoption='var1')
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{'od2.var4': None, 'od2.var5': None, 'od2.var6': None, 'od2.var1': u'value',
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'od1.var1': None, 'od1.var3': None, 'od1.var2': None}
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>>> print c.make_dict(withoption='var1', withvalue=u'value')
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{'od2.var4': None, 'od2.var5': None, 'od2.var6': None, 'od2.var1': u'value'}
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and of course, :meth:`~config.SubConfig.make_dict()` can be called in a subtree:
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>>> print c.od1.make_dict(withoption='var1')
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{'var1': None, 'var3': None, 'var2': None}
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the owners
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~~~~~~~~~~~
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When a value is set on an option, an owner is set too, that's why one can know
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at any time if a value is a default value or not. Let's create a tree::
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>>> var1 = UnicodeOption('var1', '', u'oui')
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>>> od1 = OptionDescription('od1', '', [var1])
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>>> rootod = OptionDescription('rootod', '', [od1])
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>>> c = Config(rootod)
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>>> c.read_write()
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Then let's retrieve the owner associated to an option::
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>>> print c.getowner('var1')
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default
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>>> c.od1.var1 = u'non'
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>>> print c.getowner('var1')
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user
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>>> del(c.var1)
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>>> print c.getowner('var1')
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default
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the properties
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~~~~~~~~~~~~~~~~
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A property is an information on an option's state.
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Let's create options with properties::
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>>> var1 = UnicodeOption('var1', '', u'value', properties=('hidden',))
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>>> var2 = UnicodeOption('var2', '', properties=('mandatory',))
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>>> var3 = UnicodeOption('var3', '', u'value', properties=('frozen', 'inconnu'))
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>>> var4 = UnicodeOption('var4', '', u'value')
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>>> od1 = OptionDescription('od1', '', [var1, var2, var3])
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>>> od2 = OptionDescription('od2', '', [var4], properties=('hidden',))
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>>> rootod = OptionDescription('rootod', '', [od1, od2])
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>>> c = Config(rootod)
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>>> c.read_write()
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A hidden value is a value that cannot be accessed in read/write mode. This
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option cannot be modified any more. Let's try to access to an option's value
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with a hidden option::
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>>> print c.od1.var1
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named: var1
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with properties ['hidden']
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>>> c.read_only()
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>>> print c.od1.var1
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value
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A mandatory option is an option with a value that shall not be `None`. The
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value has to be defined. Accessing to such an option is easy in read/write
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mode. But in read only mode, an error is raised if no value has been defined::
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>>> c.read_write()
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>>> print c.od1.var2
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None
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>>> c.read_only()
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>>> print c.od1.var2
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named: var2
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with properties ['mandatory']
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>>> c.read_write()
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>>> c.od1.var2 = u'value'
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>>> c.read_only()
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>>> print c.od1.var2
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value
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A frozen option, is an option that cannot be modified by a user.
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Let's try to modify a frozen option::
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>>> c.read_write()
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>>> print c.od1.var3
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value
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>>> c.od1.var3 = u'value2'
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: cannot change the value for option var3 this option is frozen
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>>> c.read_only()
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>>> print c.od1.var3
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value
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Tiramisu allows us to use user defined properties. Let's define and use one in
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read/write or read only mode::
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>>> c.cfgimpl_get_settings().append('inconnu')
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>>> print c.od1.var3
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named:
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var3 with properties ['inconnu']
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>>> c.cfgimpl_get_settings().remove('inconnu')
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>>> print c.od1.var3
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value
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Properties can also be defined on option groups,
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(that is, on :ref:`option description`s), let's hide a group and try to access to it::
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>>> c.read_write()
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>>> print c.od2.var4
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named: od2
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with properties ['hidden']
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>>> c.read_only()
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>>> print c.od2.var4
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value
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Furthermore, let's retrieve the properties, delete and add the `hidden` property::
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>>> c.read_write()
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>>> c.cfgimpl_get_settings()[rootod.od1.var1]
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['hidden']
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>>> print c.od1.var1
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named:
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var1 with properties ['hidden']
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>>> c.cfgimpl_get_settings()[rootod.od1.var1].remove('hidden')
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>>> c.cfgimpl_get_settings()[rootod.od1.var1]
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[]
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>>> print c.od1.var1
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value
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>>> c.cfgimpl_get_settings()[rootod.od1.var1].append('hidden')
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>>> c.cfgimpl_get_settings()[rootod.od1.var1]
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['hidden']
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>>> print c.od1.var1
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named:
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var1 with properties ['hidden']
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The requirements
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~~~~~~~~~~~~~~~~~~
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Let's create an option wich has requirements::
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>>> var1 = UnicodeOption('var1', '', u'value', requires=(('od1.var2',
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'non', 'hidden'),))
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>>> var2 = UnicodeOption('var2', '', u'oui')
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>>> var3 = UnicodeOption('var3', '', u'value', requires=(('od1.var2',
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'non', 'hidden'), ('od1.var2', 'non', 'disabled')))
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>>> var4 = UnicodeOption('var4', '', u'oui')
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>>>
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>>> od1 = OptionDescription('od1', '', [var1, var2, var3])
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>>> od2 = OptionDescription('od2', '', [var4], requires=(('od1.var2',
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'oui', 'hidden', True),))
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>>> rootod = OptionDescription('rootod', '', [od1, od2])
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>>> c = Config(rootod)
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>>> c.read_write()
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The requirement here is the tuple `('od1.var2' , 'non', 'hidden')` wich means
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that is the option `'od1.var2'` is set to `'non'`, the option `'od1.var1'` is
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gonna be hidden. On the other hand, if the option `'od1.var2'` is different
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from `'non'`, the option `'od1.var1'` is not hidden any more::
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>>> print c.cfgimpl_get_settings()[rootod.od1.var1]
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[]
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>>> print c.od1.var1
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value
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>>> print c.od1.var2
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oui
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>>> c.od1.var2 = u'non'
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>>> print c.cfgimpl_get_settings()[rootod.od1.var1]
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['hidden']
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>>> print c.od1.var1
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named:
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var1 with properties ['hidden']
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>>> c.od1.var2 = u'oui'
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>>> print c.cfgimpl_get_settings()[rootod.od1.var1]
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[]
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>>> print c.od1.var1
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value
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The requirement on `od2` is `('od1.var2', 'oui', 'hidden', True)`, which means
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that if the option `od1.var2` is set to `oui`, the option is not hidden
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(because of the `True` at the end of the tuple wich means 'inverted', take a
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look at the :doc:`consistency` document.)::
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>>> print c.od2.var4
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oui
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>>> c.od1.var2 = u'non'
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>>> print c.od2.var4
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Traceback (most recent call last):
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[...]
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tiramisu.error.PropertiesOptionError: trying to access to an option named: od2 with properties ['hidden']
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>>> c.od1.var2 = u'oui'
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>>> print c.od2.var4
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oui
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Requirements can be accumulated
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>>> print c.cfgimpl_get_settings()[rootod.od1.var3]
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[]
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>>> c.od1.var2 = u'non'
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>>> print c.cfgimpl_get_settings()[rootod.od1.var3]
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['disabled', 'hidden']
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>>> c.od1.var2 = u'oui'
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>>> print c.cfgimpl_get_settings()[rootod.od1.var3]
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[]
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Requirements can be accumulated for different or identical properties (inverted
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or not)::
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>>> a = UnicodeOption('var3', '', u'value', requires=(('od1.var2', 'non',
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'hidden'), ('od1.var1', 'oui', 'hidden')))
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>>> a = UnicodeOption('var3', '', u'value', requires=(('od1.var2', 'non',
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'hidden'), ('od1.var1', 'oui', 'disabled', True)))
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But it is not possible to have inverted requirements on the same property.
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Here is an impossible situation::
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>>> a = UnicodeOption('var3', '', u'value', requires=(('od1.var2', 'non',
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'hidden'), ('od1.var1', 'oui', 'hidden', True)))
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Traceback (most recent call last):
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[...]
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ValueError: inconsistency in action types for option: var3 action: hidden
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Configuration's interesting methods
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------------------------------------------
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A `Config` object is informed by an `option.OptionDescription`
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instance. The attributes of the ``Config`` objects are the names of the
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children of the ``OptionDescription``.
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Here are the (useful) methods on ``Config`` (or `SubConfig`).
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.. currentmodule:: tiramisu.config
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.. class:: Config
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.. autoclass:: SubConfig
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:members: find, find_first, __iter__, iter_groups, iter_all, make_dict
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.. automethod:: __init__
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.. rubric:: Summary
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.. autosummary::
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find
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find_first
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__iter__
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iter_groups
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iter_all
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make_dict
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.. rubric:: Methods
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A :class:`~config.CommonConfig` is a abstract base class. A
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:class:`~config.SubConfig` is an just in time created objects that wraps an
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::class:`~option.OptionDescription`. A SubConfig differs from a Config in the
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::fact that a config is a root object and has an environnement, a context wich
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::defines the different properties, access rules, vs... There is generally only
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::one Config, and many SubConfigs.
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