renamed package to pypattyrn

pypattyrn/structural/composite.py

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