front.elements.tree_maker_base#

ElementTreeMaker: builds the composite tree of front elements from a rendering spec.

The tree is then walked by AppMaker to produce the runnable app. Concrete frontends typically don’t override this — they supply their own element classes via the rendering specification.

Classes

ElementTreeMaker()

Build the composite tree of front elements from a compiled rendering spec.

class front.elements.tree_maker_base.ElementTreeMaker[source]#

Bases: object

Build the composite tree of front elements from a compiled rendering spec.

The rendering specification maps ELEMENT_KEY to the root container factory, and types (or names) of the objects to render to their element specs. The resulting tree is rendered by calling its root, which renders each element recursively.

>>> from collections.abc import Callable
>>> from front.elements import FrontContainerBase, FrontComponentBase, ELEMENT_KEY
>>> class App(FrontContainerBase):
...     def render(self):
...         return {child.name: child() for child in self.children}
>>> class Doc(FrontComponentBase):
...     def render(self):
...         return self.obj.__doc__
>>> def foo(a, b):
...     "Adds a and b."
...     return a + b
>>> rendering_spec = {ELEMENT_KEY: App, Callable: {ELEMENT_KEY: Doc}}
>>> tree = ElementTreeMaker().mk_tree([foo], rendering_spec)
>>> type(tree).__name__, [type(child).__name__ for child in tree.children]
('App', ['Doc'])
>>> tree()
{'foo': 'Adds a and b.'}