73 lines
2.5 KiB
Python
73 lines
2.5 KiB
Python
class Composite(object):
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"""
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Composite class as part of the Composite pattern.
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External Composite Pattern documentation: U{https://en.wikipedia.org/wiki/Composite_pattern}
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"""
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def __init__(self, interface):
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"""
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Initialize a new Composite instance.
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@param interface: The interface the all child components must adhere to when added to this composite.
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@type interface: class
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"""
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self.components = set()
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self.interface = interface
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def add_component(self, component):
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"""
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Add a component to this composite.
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@param component: The component to add to this Composite
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@raise AttributeError: If the component does not adhere to this Composites interface.
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"""
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valid = False
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try:
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if component.interface == self.interface:
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valid = True
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except AttributeError:
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if self.interface in component.__class__.__mro__:
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valid = True
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finally:
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if valid:
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self.components.add(component)
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else:
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raise AttributeError('Component {0} does not follow this composites interface {1}'.format(
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component.__class__, self.interface))
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def remove_component(self, component):
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"""
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Remove a component from this composite.
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@param component: The component to remove from this Composite.
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"""
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try:
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self.components.remove(component)
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except KeyError:
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pass
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def _delegate(self, func_name):
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"""
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Apply a function to all child components by function name.
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@param func_name: The name of the function to call with all child components.
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@type func_name: str
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@raise AttributeError: If a child component does not have a callable function with the given name.
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"""
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for component in self.components:
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attribute = getattr(component, func_name)
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if callable(attribute):
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attribute()
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else:
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raise AttributeError()
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def __getattr__(self, item):
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"""
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Override getattr to delegate all function calls to children.
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@param item: The function to call with this composites children components.
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@type item: str
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@return: A function that when called will call all child functions with the given function name.
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"""
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return lambda: self._delegate(item)
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