今天逛github的时候看到这样一个项目，其中在RPC远程调用接口中实现一个功能，并用add_method进行装饰，于是我把它从项目中摘出来。
并在此基础上，我额外增加了add_missing_method方法，用于包装一个自定义方法，处理拦截未找到方法的情况。
以下代码演示了如何动态调用函数、方法。
代码语言：python代码运行次数：0复制# -*- coding: utf-8 -*-
import functools
try:
from collections.abc import MutableMapping
except ImportError:
from collections import MutableMapping
class Dispatcher(MutableMapping):
""" Dictionary like object which maps method_name to method."""
def __init__(self, prototype=None):
""" Build method dispatcher.
Parameters
----------
prototype : object or dict, optional
Initial method mapping.
Examples
--------
Init object with method dictionary.
>>> Dispatcher({"sum": lambda a, b: a b})
None
"""
self.missing_method_name = '__missing__'
self.method_map = dict()
if prototype is not None:
self.build_method_map(prototype)
def __getitem__(self, key):
if key in self.method_map:
return self.method_map[key]
if self.missing_method_name in self.method_map:
return self.method_map[self.missing_method_name]
raise Exception('missing method <' key '> if you want to close the Exception, you can use '
'add_missing_method.')
def __setitem__(self, key, value):
self.method_map[key] = value
def __delitem__(self, key):
del self.method_map[key]
def __len__(self):
return len(self.method_map)
def __iter__(self):
return iter(self.method_map)
def __repr__(self):
return repr(self.method_map)
def add_class(self, cls):
prefix = cls.__name__.lower() '.'
self.build_method_map(cls(), prefix)
def add_object(self, obj):
prefix = obj.__class__.__name__.lower() '.'
self.build_method_map(obj, prefix)
def add_dict(self, dict, prefix=''):
if prefix:
prefix = '.'
self.build_method_map(dict, prefix)
def add_method(self, f=None, name=None):
""" Add a method to the dispatcher.
Parameters
----------
f : callable
Callable to be added.
name : str, optional
Name to register (the default is function **f** name)
Notes
-----
When used as a decorator keeps callable object unmodified.
Examples
--------
Use as method
>>> d = Dispatcher()
>>> d.add_method(lambda a, b: a b, name="sum")
<function __main__.<lambda>>
Or use as decorator
>>> d = Dispatcher()
>>> @d.add_method
def mymethod(*args, **kwargs):
print(args, kwargs)
Or use as a decorator with a different function name
>>> d = Dispatcher()
>>> @d.add_method(name="my.method")
def mymethod(*args, **kwargs):
print(args, kwargs)
"""
if name and not f:
return functools.partial(self.add_method, name=name)
self.method_map[name or f.__name__] = f
return f
def add_missing_method(self, f=None, name=None):
""" Add missing method to the dispatcher"""
self.missing_method_name = name
return self.add_method(f, name)
def build_method_map(self, prototype, prefix=''):
""" Add prototype methods to the dispatcher.
Parameters
----------
prototype : object or dict
Initial method mapping.
If given prototype is a dictionary then all callable objects will
be added to dispatcher.
If given prototype is an object then all public methods will
be used.
prefix: string, optional
Prefix of methods
"""
if not isinstance(prototype, dict):
prototype = dict((method, getattr(prototype, method))
for method in dir(prototype)
if not method.startswith('_'))
for attr, method in prototype.items():
if callable(method):
self[prefix attr] = method
if __name__ == '__main__':
d = Dispatcher()
d.add_method(lambda a, b: a b, name="sum")
d.add_method(lambda a, b: a - b, name="sub")
d.add_method(lambda a, b: a * b, name="mul")
@d.add_method(name="miclon")
def method(*args, **kwargs):
print(args, kwargs)
return "miclon"
@d.add_class
class MyClass:
def __init__(self):
self.a = 1
def method(self, b):
return self.a b
@d.add_missing_method(name='__miss__')
def missing_method(*args, **kwargs):
print("未找到接收调用的方法", args, kwargs)
print(d['sum'](1, 2))
# 3
print(d['miclon']('a', {'b': 'c'}, 'd'))
# ('a', {'b': 'c'}, 'd') {}
print(d['myclass.method'](2))
# 3
print(d['qqqqq'](2))
# 未找到接收调用的方法
Dispatcher是一个类似字典的对象，它负责存储方法，并且提供一个字典存储方法的名称和方法的映射。
实际调用端可以通过方法名称来动态的调用方法，也可以通过方法名称来获取方法。
它没有任何限制，你要做的就是暴露公共的实例化Dispatcher类。
然后通过：add_method方法添加方法，add_class方法添加类，add_object方法添加对象，add_dict方法添加字典(字典中也是方法的名称和方法的映射)，add_missing_method方法添加当引用一个不存在方法的时候的默认方法。
