add magic methods

Author: michaelliao

py3/oop_advance/special_call.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+class Student(object):
+    def __init__(self, name):
+        self.name = name
+
+    def __call__(self):
+        print('My name is %s.' % self.name)
+
+s = Student('Michael')
+s()

py3/oop_advance/special_getattr.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+class Student(object):
+
+    def __init__(self):
+        self.name = 'Michael'
+
+    def __getattr__(self, attr):
+        if attr=='score':
+            return 99
+        if attr=='age':
+            return lambda: 25
+        raise AttributeError('\'Student\' object has no attribute \'%s\'' % attr)
+
+s = Student()
+print(s.name)
+print(s.score)
+print(s.age())
+# AttributeError: 'Student' object has no attribute 'grade'
+print(s.grade)

py3/oop_advance/special_getitem.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+class Fib(object):
+
+    def __getitem__(self, n):
+        if isinstance(n, int):
+            a, b = 1, 1
+            for x in range(n):
+                a, b = b, a + b
+            return a
+        if isinstance(n, slice):
+            start = n.start
+            stop = n.stop
+            if start is None:
+                start = 0
+            a, b = 1, 1
+            L = []
+            for x in range(stop):
+                if x >= start:
+                    L.append(a)
+                a, b = b, a + b
+            return L
+
+f = Fib()
+print(f[0])
+print(f[5])
+print(f[100])
+print(f[0:5])
+print(f[:10])

py3/oop_advance/special_iter.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+class Fib(object):
+
+    def __init__(self):
+        self.a, self.b = 0, 1 # 初始化两个计数器a，b
+
+    def __iter__(self):
+        return self # 实例本身就是迭代对象，故返回自己
+
+    def __next__(self):
+        self.a, self.b = self.b, self.a + self.b # 计算下一个值
+        if self.a > 100000: # 退出循环的条件
+            raise StopIteration();
+        return self.a # 返回下一个值
+
+for n in Fib():
+    print(n)

py3/oop_advance/special_str.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+class Student(object):
+
+    def __init__(self, name):
+        self.name = name
+
+    def __str__(self):
+        return 'Student object (name: %s)' % self.name
+
+    __repr__ = __str__
+
+print(Student('Michael'))

py3/oop_advance/use_property.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+class Student(object):
+
+    @property
+    def score(self):
+        return self._score
+
+    @score.setter
+    def score(self, value):
+        if not isinstance(value, int):
+            raise ValueError('score must be an integer!')
+        if value < 0 or value > 100:
+            raise ValueError('score must between 0 ~ 100!')
+        self._score = value
+
+s = Student()
+s.score = 60
+print('s.score =', s.score)
+# ValueError: score must between 0 ~ 100!
+s.score = 9999