gistfile1.py

class MultiLoader(object):
    def __init__(self):
        self.d = {}

    def load(self, values):
        for k, v in zip(self.keys, values):
            if k:
                self.d[k] = self.process(k, v)
    
    def process(self, key, value):
        action = getattr(self, 'proc_'+key, self.default_action)
        return action(value)

class MultiLoaderPlus(MultiLoader):
    def load(self, values):
        pairs = []
        for ks, v in zip(self.keys, values):                
            if isinstance(ks, basestring):
                self.d[ks] = self.process(ks, v)
            else:
                for k in ks:
                    self.d[k] = self.process(k, v)

class MyLoader(MultiLoaderPlus):
    keys = ['aaa', ('bbb', 'ccc'), 'ddd']

    default_action = lambda s, x: x.upper()

    proc_ccc = lambda s, x: x*5

if __name__ == '__main__':
    loader = MyLoader()
    loader.load(['foo', 'bar', 'baz'])
    print loader.d