front.spec_maker_base#

Base classes and conventions for building a FrontSpec from a configuration.

A spec maker is the “short language → long language” compiler of front: it consumes a user configuration plus a convention (defaults) and emits the nested app / obj / rendering specification consumed by AppMaker.

Classes

SpecMakerBase()

Compile a user configuration (short language) into a FrontSpec (long language).

class front.spec_maker_base.SpecMakerBase[source]#

Bases: ABC

Compile a user configuration (short language) into a FrontSpec (long language).

The configuration is merged over a convention (the defaults), then the class-keyed entries of the rendering specification are completed along the class hierarchy, so that a spec for a subclass inherits the spec of its bases.

To do so, the “mk_spec” method first merges the configuration with the convention, then does the following for the rendering specification: Let’s consider we have three classes A, B and C with C extends B and B extends A (A <- B <- C). If the rendering configuration contains the following:

{
    A: {
        'a': {...}
    },
    B: {
        'b': {...}
    },
    C: {
        'c': {...}
    },
}

The resulting rendering specification will be:

{
    A: {
        'a': {...}
    },
    B: {
        'a': {...},
        'b': {...}
    },
    C: {
        'a': {...},
        'b': {...},
        'c': {...}
    },
}

This abstract class needs to be overloaded in every concrete front framework with a concrete implementation for the “_dflt_convention” property, which will return the convention after injecting the concrete element factories in it.

>>> from front import APP_KEY, OBJ_KEY, RENDERING_KEY
>>> from front.util import dflt_trans
>>> class A: pass
>>> class B(A): pass
>>> class C(B): pass
>>> class SpecMaker(SpecMakerBase):
...     @property
...     def _dflt_convention(self):
...         return {
...             APP_KEY: {'title': 'Untitled'},
...             OBJ_KEY: {'trans': dflt_trans},
...             RENDERING_KEY: {A: {'a': 1}, B: {'b': 2}, C: {'c': 3}},
...         }
>>> spec = SpecMaker().mk_spec({APP_KEY: {'title': 'Demo'}})
>>> spec.app_spec
{'title': 'Demo'}
>>> spec.rendering_spec[C]
{'a': 1, 'b': 2, 'c': 3}
>>> spec.rendering_spec[B]
{'a': 1, 'b': 2}