看一下注册机制是如何使用的：
registry_machine = Registry('registry_machine')registry_machine.register()
def print_hello_world(word):print('hello {}'.format(word))registry_machine.register()
def print_hi_world(word):print('hi {}'.format(word))if __name__ == '__main__':cfg1 = 'print_hello_word'registry_machine.get(cfg1)('world')cfg2 = 'print_hi_word'registry_machine.get(cfg2)('world')可以看到，如果创建了一个Registry的对象，并在方法/类定义的时候用装饰器装饰它，则可以通过 registry_machine.get(方法名)的 办法来间接的调用被注册的函数
具体实现细节，注册类的代码
class Registry(object):def __init__(self, name):"""Args:name (str): the name of this registry"""self._name = nameself._obj_map = {}def _do_register(self, name, obj):assert (name not in self._obj_map), "An object named '{}' was already registered in '{}' registry!".format(name, self._name)self._obj_map[name] = objdef register(self, obj=None):"""Register the given object under the the name `obj.__name__`.Can be used as either a decorator or not. See docstring of this class for usage."""if obj is None:# used as a decoratordef deco(func_or_class):name = func_or_class.__name__self._do_register(name, func_or_class)return func_or_classreturn deco# used as a function callname = obj.__name__self._do_register(name, obj)def get(self, name):ret = self._obj_map.get(name)if ret is None:raise KeyError("No object named '{}' found in '{}' registry!".format(name, self._name))return retregistry_machine = Registry('registry_machine')registry_machine.register()
def print_hello_world(word):print('hello {}'.format(word))registry_machine.register()
def print_hi_world(word):print('hi {}'.format(word))if __name__ == '__main__':cfg1 = 'print_hello_word'registry_machine.get(cfg1)('world')cfg2 = 'print_hi_word'registry_machine.get(cfg2)('world')