add python_decorator.py

Author: xianhu

README.md

@@ -1,7 +1,7 @@
 # LearnPython
 以撸代码的形式学习Python, 具体说明在[知乎专栏-撸代码,学知识](https://zhuanlan.zhihu.com/pythoner)
 
-============================================================
+===============================================================================
 ### python_base.py: 千行代码入门Python
 
 ### python_visual.py: 15张图入门Matplotlib
@@ -19,6 +19,8 @@
 ### python_requests.py: Python中最好用的爬虫库Requests代码实例
 
 ### python_functional.py: Python进阶: 函数式编程实例（附代码）
-============================================================
+
+### python_decorator.py: Python进阶: 通过实例详解装饰器（附代码）
+===============================================================================
 
 ### 您可以fork该项目,并在修改后提交Pull request

python_decorator.py

@@ -0,0 +1,190 @@
+# _*_ coding: utf-8 _*_
+
+"""
+python_decorator.py by xianhu
+"""
+
+import functools
+
+
+# 构建不太参数的装饰器
+def logging(func):
+ @functools.wraps(func)
+ def decorator(*args, **kwargs):
+ print("%s called" % func.__name__)
+ result = func(*args, **kwargs)
+ print("%s end" % func.__name__)
+ return result
+ return decorator
+
+
+# 使用装饰器
+@logging
+def test01(a, b):
+ print("in function test01, a=%s, b=%s" % (a, b))
+ return 1
+
+
+# 使用装饰器
+@logging
+def test02(a, b, c=1):
+ print("in function test02, a=%s, b=%s, c=%s" % (a, b, c))
+ return 1
+
+
+# 构建带参数的装饰器
+def params_chack(*types, **kwtypes):
+ def _outer(func):
+ @functools.wraps(func)
+ def _inner(*args, **kwargs):
+ result = [isinstance(_param, _type) for _param, _type in zip(args, types)]
+ assert all(result), "params_chack: invalid parameters"
+ result = [isinstance(kwargs[_param], kwtypes[_param]) for _param in kwargs if _param in kwtypes]
+ assert all(result), "params_chack: invalid parameters"
+ return func(*args, **kwargs)
+ return _inner
+ return _outer
+
+
+# 使用装饰器
+@params_chack(int, (list, tuple))
+def test03(a, b):
+ print("in function test03, a=%s, b=%s" % (a, b))
+ return 1
+
+
+# 使用装饰器
+@params_chack(int, str, c=(int, str))
+def test04(a, b, c):
+ print("in function test04, a=%s, b=%s, c=%s" % (a, b, c))
+ return 1
+
+
+# 在类的成员方法中使用装饰器
+class ATest(object):
+ @params_chack(object, int, str)
+ def test(self, a, b):
+ print("in function test of ATest, a=%s, b=%s" % (a, b))
+ return 1
+
+
+# 同时使用多个装饰器
+@logging
+@params_chack(int, str, (list, tuple))
+def test05(a, b, c):
+ print("in function test05, a=%s, b=%s, c=%s" % (a, b, c))
+ return 1
+
+
+# 构建不带参数的装饰器类
+class Decorator(object):
+
+ def __init__(self, func):
+ self.func = func
+ return
+
+ def __call__(self, *args, **kwargs):
+ print("%s called" % self.func.__name__)
+ result = self.func(*args, **kwargs)
+ print("%s end" % self.func.__name__)
+ return result
+
+
+# 使用装饰器
+@Decorator
+def test06(a, b, c):
+ print("in function test06, a=%s, b=%s, c=%s" % (a, b, c))
+ return 1
+
+
+# 构建带参数的装饰器类
+class ParamCheck(object):
+
+ def __init__(self, *types, **kwtypes):
+ self.types = types
+ self.kwtypes = kwtypes
+ return
+
+ def __call__(self, func):
+ @functools.wraps(func)
+ def _inner(*args, **kwargs):
+ result = [isinstance(_param, _type) for _param, _type in zip(args, self.types)]
+ assert all(result), "params_chack: invalid parameters"
+ result = [isinstance(kwargs[_param], self.kwtypes[_param]) for _param in kwargs if _param in self.kwtypes]
+ assert all(result), "params_chack: invalid parameters"
+ return func(*args, **kwargs)
+ return _inner
+
+
+# 使用装饰器
+@ParamCheck(int, str, (list, tuple))
+def test07(a, b, c):
+ print("in function test06, a=%s, b=%s, c=%s" % (a, b, c))
+ return 1
+
+
+# 装饰器实例: 函数缓存
+def funccache(func):
+ cache = {}
+
+ @functools.wraps(func)
+ def _inner(*args):
+ if args not in cache:
+ cache[args] = func(*args)
+ return cache[args]
+ return _inner
+
+
+# 使用装饰器
+@funccache
+def test08(a, b, c):
+ # 其他复杂或耗时计算
+ return a + b + c
+
+
+# 使用Python自带的装饰器
+class People(object):
+
+ def __init__(self):
+ self._name = None
+ self._age = None
+ return
+
+ @property
+ def name(self):
+ return self._name
+
+ @name.setter
+ def name(self, name):
+ self._name = name
+ return
+
+ @property
+ def age(self):
+ return self._age
+
+ @age.setter
+ def age(self, age):
+ assert 0 < age < 120
+ self._age = age
+ return
+
+
+# 类静态方法和类方法
+class A(object):
+ var = 1
+
+ def func(self):
+ print(self.var)
+ return
+
+ @staticmethod
+ def static_func():
+ print(A.var)
+ return
+
+ @classmethod
+ def class_func(cls):
+ print(cls.var)
+ cls().func()
+ return