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