add python_metaclass.py

Author: xianhu

README.md

@@ -23,6 +23,8 @@
 ### python_decorator.py: Python进阶: 通过实例详解装饰器（附代码）
 
 ### python_datetime.py: 你真的了解Python中的日期时间处理吗？
+
+### python_metaclass.py: Python进阶: 一步步理解Python中的元类metaclass
 ===============================================================================
 
 ### 您可以fork该项目,并在修改后提交Pull request

python_metaclass.py

@@ -0,0 +1,55 @@
+# _*_ coding: utf-8 _*_
+
+"""
+python_metaclass.py by xianhu
+"""
+
+
+class Foo:
+ def hello(self):
+ print("hello world!")
+ return
+
+foo = Foo()
+print(type(foo)) # <class '__main__.Foo'>
+print(type(foo.hello)) # <class 'method'>
+print(type(Foo)) # <class 'type'>
+
+temp = Foo # 赋值给其他变量
+Foo.var = 11 # 增加参数
+print(Foo) # 作为函数参数
+
+
+# ========================================================================
+def init(self, name):
+ self.name = name
+ return
+
+
+def hello(self):
+ print("hello %s" % self.name)
+ return
+
+Foo = type("Foo", (object,), {"__init__": init, "hello": hello, "cls_var": 10})
+foo = Foo("xianhu")
+print(foo.hello())
+print(Foo.cls_var)
+
+print(foo.__class__)
+print(Foo.__class__)
+print(type.__class__)
+# ========================================================================
+
+
+class Author(type):
+ def __new__(mcs, name, bases, dict):
+ # 添加作者属性
+ dict["author"] = "xianhu"
+ return super(Author, mcs).__new__(mcs, name, bases, dict)
+
+
+class Foo(object, metaclass=Author):
+ pass
+
+foo = Foo()
+print(foo.author)