组合模式

所谓组合模式就是利用对象组合成整体结构,简单的说就是节点的反复嵌套,类似tree结构

 

参考代码:

"""A class which defines a composite object which can storehieararchical dictionaries with names.This class is same as a hiearchical dictionary, but itprovides methods to add/access/modify children by name, like a Composite.Created Anand B Pillai     <[e-mail]>"""__author__ = "Anand B Pillai"__maintainer__ = "Anand B Pillai"__version__ = "0.2"def normalize(val):    """ Normalize a string so that it can be used as an attribute    to a Python object """        if val.find('-') != -1:        val = val.replace('-', '_')    return valdef denormalize(val):    """ De-normalize a string """    if val.find('_') != -1:        val = val.replace('_', '-')    return valclass SpecialDict(dict):    """ A dictionary type which allows direct attribute    access to its keys """    def __getattr__(self, name):        if name in self.__dict__:            return self.__dict__[name]        elif name in self:            return self.get(name)        else:            # Check for denormalized name            name = denormalize(name)            if name in self:                return self.get(name)            else:                raise AttributeError('no attribute named %s' % name)    def __setattr__(self, name, value):        if name in self.__dict__:            self.__dict__[name] = value        elif name in self:            self[name] = value        else:            # Check for denormalized name            name2 = denormalize(name)            if name2 in self:                self[name2] = value            else:                # New attribute                self[name] = value        class CompositeDict(SpecialDict):    """ A class which works like a hierarchical dictionary.    This class is based on the Composite design-pattern """    ID = 0    def __init__(self, name=''):        if name:            self._name = name        else:            self._name = ''.join(('id#', str(self.__class__.ID)))            self.__class__.ID += 1        self._children = []        # Link  back to father        self._father = None        self[self._name] = SpecialDict()    def __getattr__(self, name):        if name in self.__dict__:            return self.__dict__[name]        elif name in self:            return self.get(name)        else:            # Check for denormalized name            name = denormalize(name)            if name in self:                return self.get(name)            else:                # Look in children list                child = self.findChild(name)                if child:                    return child                else:                    attr = getattr(self[self._name], name)                    if attr:                        return attr                                        raise AttributeError('no attribute named %s' % name)    def isRoot(self):        """ Return whether I am a root component or not """        # If I don't have a parent, I am root        return not self._father        def isLeaf(self):        """ Return whether I am a leaf component or not """        # I am a leaf if I have no children        return not self._children    def getName(self):        """ Return the name of this ConfigInfo object """        return self._name    def getIndex(self, child):        """ Return the index of the child ConfigInfo object 'child' """                if child in self._children:            return self._children.index(child)        else:            return -1    def getDict(self):        """ Return the contained dictionary """                return self[self._name]    def getProperty(self, child, key):        """ Return the value for the property for child        'child' with key 'key' """        # First get the child's dictionary        childDict = self.getInfoDict(child)        if childDict:            return childDict.get(key, None)    def setProperty(self, child, key, value):        """ Set the value for the property 'key' for        the child 'child' to 'value' """        # First get the child's dictionary        childDict = self.getInfoDict(child)        if childDict:            childDict[key] = value        def getChildren(self):        """ Return the list of immediate children of this object """                return self._children    def getAllChildren(self):        """ Return the list of all children of this object """                l = []        for child in self._children:            l.append(child)            l.extend(child.getAllChildren())                    return l    def getChild(self, name):        """ Return the immediate child object with the given name """                for child in self._children:            if child.getName() == name:                return child    def findChild(self, name):        """ Return the child with the given name from the tree """        # Note - this returns the first child of the given name        # any other children with similar names down the tree        # is not considered.                for child in self.getAllChildren():            if child.getName() == name:                return child    def findChildren(self, name):        """ Return a list of children with the given name from the tree """        # Note: this returns a list of all the children of a given        # name, irrespective of the depth of look-up.                children = []                for child in self.getAllChildren():            if child.getName() == name:                children.append(child)        return children                def getPropertyDict(self):        """ Return the property dictionary """                d = self.getChild('__properties')        if d:            return d.getDict()        else:            return {}            def getParent(self):        """ Return the person who created me """        return self._father        def __setChildDict(self, child):        """ Private method to set the dictionary of the child        object 'child' in the internal dictionary """                d = self[self._name]        d[child.getName()] = child.getDict()    def setParent(self, father):        """ Set the parent object of myself """        # This should be ideally called only once        # by the father when creating the child :-)        # though it is possible to change parenthood        # when a new child is adopted in the place        # of an existing one - in that case the existing        # child is orphaned - see addChild and addChild2        # methods !        self._father = father            def setName(self, name):        """ Set the name of this ConfigInfo object to 'name' """                self._name = name    def setDict(self, d):        """ Set the contained dictionary """                self[self._name] = d.copy()            def setAttribute(self, name, value):        """ Set a name value pair in the contained dictionary """                self[self._name][name] = value    def getAttribute(self, name):        """ Return value of an attribute from the contained dictionary """                return self[self._name][name]    def addChild(self, name, force=False):        """ Add a new child 'child' with the name 'name'.        If the optional flag 'force' is set to True, the        child object is overwritten if it is already there.        This function returns the child object, whether        new or existing """                if type(name) != str:            raise ValueError('Argument should be a string!')                child = self.getChild(name)        if child:            # print 'Child %s present!' % name            # Replace it if force==True            if force:                index = self.getIndex(child)                if index != -1:                    child = self.__class__(name)                    self._children[index] = child                    child.setParent(self)                                        self.__setChildDict(child)            return child        else:            child = self.__class__(name)            child.setParent(self)                        self._children.append(child)            self.__setChildDict(child)            return child            def addChild2(self, child):        """ Add the child object 'child'. If it is already present,        it is overwritten by default """                currChild = self.getChild(child.getName())        if currChild:            index = self.getIndex(currChild)            if index != -1:                self._children[index] = child                child.setParent(self)                # Unset the existing child's parent                currChild.setParent(None)                del currChild                                self.__setChildDict(child)        else:            child.setParent(self)                        self._children.append(child)            self.__setChildDict(child)if __name__ == "__main__":    window = CompositeDict('Window')    frame = window.addChild('Frame')    tfield = frame.addChild('Text Field')    tfield.setAttribute('size', '20')        btn = frame.addChild('Button1')    btn.setAttribute('label', 'Submit')    btn = frame.addChild('Button2')    btn.setAttribute('label', 'Browse')    # print(window)    # print(window.Frame)    # print(window.Frame.Button1)    # print(window.Frame.Button2)    print(window.Frame.Button1.label)    print(window.Frame.Button2.label)