example1.py 文件源码

def register(self, meth):
        '''
        Register a new method as a multimethod
        '''
        sig = inspect.signature(meth)

        # Build a type-signature from the method's annotations
        types = []
        for name, parm in sig.parameters.items():
            if name == 'self': 
                continue
            if parm.annotation is inspect.Parameter.empty:
                raise TypeError(
                    'Argument {} must be annotated with a type'.format(name)
                    )
            if not isinstance(parm.annotation, type):
                raise TypeError(
                    'Argument {} annotation must be a type'.format(name)
                    )
            if parm.default is not inspect.Parameter.empty:
                self._methods[tuple(types)] = meth
            types.append(parm.annotation)

        self._methods[tuple(types)] = meth