Source Code for Module pypat.structural.composite

 1 -class Composite(object): 
 2      """ 
 3      Composite class as part of the Composite pattern. 
 4   
 5      - External Usage Documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Structural-Pattern-Usage} 
 6      - External Composite Pattern documentation: U{https://en.wikipedia.org/wiki/Composite_pattern} 
 7      """ 
 8 -    def __init__(self, interface): 
 9          """ 
10          Initialize a new Composite instance. 
11   
12          @param interface: The interface the all child components must adhere to when added to this composite. 
13          @type interface: class 
14          """ 
15          self.components = set() 
16          self.interface = interface 
17   
18 -    def add_component(self, component): 
19          """ 
20          Add a component to this composite. 
21   
22          @param component: The component to add to this Composite 
23          @raise AttributeError: If the component does not adhere to this Composites interface. 
24          """ 
25          valid = False 
26          try: 
27              if component.interface == self.interface: 
28                  valid = True 
29          except AttributeError: 
30              if self.interface in component.__class__.__mro__: 
31                  valid = True 
32          finally: 
33              if valid: 
34                  self.components.add(component) 
35              else: 
36                  raise AttributeError('Component {0} does not follow this composites interface {1}'.format( 
37                      component.__class__, self.interface)) 
38   
39 -    def remove_component(self, component): 
40          """ 
41          Remove a component from this composite. 
42   
43          @param component: The component to remove from this Composite. 
44          """ 
45          try: 
46              self.components.remove(component) 
47          except KeyError: 
48              pass 
49   
50 -    def _delegate(self, func_name): 
51          """ 
52          Apply a function to all child components by function name. 
53   
54          @param func_name: The name of the function to call with all child components. 
55          @type func_name: str 
56          @raise AttributeError: If a child component does not have a callable function with the given name. 
57          """ 
58          for component in self.components: 
59              attribute = getattr(component, func_name) 
60              if callable(attribute): 
61                  attribute() 
62              else: 
63                  raise AttributeError() 
64   
65 -    def __getattr__(self, item): 
66          """ 
67          Override getattr to delegate all function calls to children. 
68   
69          @param item: The function to call with this composites children components. 
70          @type item: str 
71          @return: A function that when called will call all child functions with the given function name. 
72          """ 
73          return lambda: self._delegate(item) 
74