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diff --git a/LectureNotesOnPython.rst b/LectureNotesOnPython.rst
index fac7727..6abf332 100644
--- a/LectureNotesOnPython.rst
+++ b/LectureNotesOnPython.rst
@@ -1645,8 +1645,11 @@ copy 拷贝类中的属性， 但不会重新制作一个对象中的对象 （e
纯函数与修改函数
````````````````````````````````````````````````````
-.. code:: python
+纯函数(pure function)。
+
+修改函数(modifier function)。
+.. code:: python
class Time:
def __init__(self, h, m, s):
@@ -1654,28 +1657,241 @@ copy 拷贝类中的属性， 但不会重新制作一个对象中的对象 （e
self.minute = m
self.second = s
+ def __str__(self):
+ return '%02d:%02d:%02d' % (self.hour, self.minute, self.second)
+
+ def time_to_seconds(time):
+ minutes = time.hour * 60 + time.minute
+ seconds = minutes * 60 + time.second
+ return seconds
+
+ def seconds_to_time(seconds):
+ time = Time(0, 0, 0)
+ minutes, time.second = divmod(seconds, 60)
+ time.hour, time.minute = divmod(minutes, 60)
+ return time
+
def increment_time_pure(t, h, m, s):
''' Pure function '''
- t2 = Time(0,0,0)
- return t2
-
+ secs = time_to_seconds(t) + time_to_seconds(Time(h, m, s))
+ return seconds_to_time(secs)
+
+
def increment_time_modifier(t, h, m, s):
''' Modifier function '''
- t2 = Time(0,0,0)
- return t2
+ t.hour += h
+ t.minute += m
+ t.second += s
+
+ def increment_time_modifier2(t, h, m, s):
+ ''' Modifier function '''
+ t.second += s
+ if t.second > 59:
+ minute_from_seconds, t.second = divmod(t.second, 60)
+ t.minute += m + minute_from_seconds
+ if t.minute > 59:
+ hour_from_minutes, t.minute = divmod(t.minute, 60)
+ t.hour += h + hour_from_minutes
+
+
t = Time(6, 58, 55)
+ print(t)
ti = increment_time_pure(t, 2, 30, 50)
+ print(ti)
+ increment_time_modifier(t, 2, 30, 50)
+ print(t)
+ print(seconds_to_time(time_to_seconds(t)))
+
+
+**Designed development** . 先有总体设计，然后再有开发。比如先把时间转成秒，再把秒转成时间（hh:mm:ss）。
+
+**Prototype and patch** . 先造个原型，如果有问题，逐步修改。
+
+类中的方法，就是在类中的函数定义。对方法的调用与对函数的调用不同。 对方法的调用我们用点操作符(dot notation)。点前面是对象，点后面是方法。
+
+
+调用类方法
+````````````````````````````````````````````````````
+
+.. code:: python
+
+ class Time:
+ def __init__(self, h, m, s):
+ self.hour = h
+ self.minute = m
+ self.second = s
+
+ def print_time(self):
+ print( '%02d:%02d:%02d' % (self.hour, self.minute, self.second) )
+
+ def print_time2(time):
+ print( '%02d:%02d:%02d' % (time.hour, time.minute, time.second) )
+
+
+ t = Time(1, 30, 20)
+ Time.print_time(t)
+ Time.print_time2(t)
+ t.print_time()
+ t.print_time2()
+
+
+练习：在Time类中添加一个方法 time_to_seconds，把时间转换成秒。
+
+练习：在Time类中添加一个方法， is_after， 返回True/False。
+
+练习：在Time类中添加一个方法， __add__， 使得我们可以用加号相加两个时间。 如果是一个时间加上一个整数呢？ 或者是一个整数加上一个时间呢？ 提示：使用isinstance，__radd__。
+
+
+方法中可以定义函数
+``````````````````````````````````````````````````````
+
+.. code:: python
+
+ class Time:
+ def __init__(self, h, m, s):
+ self.hour = h
+ self.minute = m
+ self.second = s
+
+ def time_to_seconds(self):
+ minutes = self.hour * 60 + self.minute
+ seconds = minutes * 60 + self.second
+ return seconds
+
+ def increment_time(self, seconds):
+
+ def seconds_to_hhmmss(seconds):
+ minutes, seconds = divmod(seconds, 60)
+ hours, minutes = divmod(minutes, 60)
+ return hours, minutes, seconds
+
+ self.hour, self.minute, self.second = seconds_to_hhmmss(self.time_to_seconds() + seconds)
+
+ def __str__(self):
+ return '%02d:%02d:%02d' % (self.hour, self.minute, self.second)
+
+
+
+ t = Time(1, 30, 20)
+ print(t)
+ t.increment_time(3600)
+ print(t)
+
+
+在t.increment_time(3600)中， t叫做subject。
+
+接口与实现相分离。
+
+Positional argument. Keyword argument.
+
+.. code:: python
+
+
+ class Time:
+ def __init__(self, h, m=0, s=0):
+ self.hour = h
+ self.minute = m
+ self.second = s
+
+ def __str__(self):
+ return '%02d:%02d:%02d' % (self.hour, self.minute, self.second)
+
+
+ t = Time(1)
+ print(t)
+ t = Time(1, s=20)
+ print(t)
+ t = Time(1, m=30)
+ print(t)
+ t = Time(1, 30, 20)
+ print(t)
+
+
+
+多态 (polymorphism)
+```````````````````````````````````````````````````
+
+如果函数可以对多个类型使用，我们把它叫做多态函数。 如histogram，可以对字符串使用去数里面字符的频率， 也可以对列表使用去数里面元素的频率。
+
+如系统自带的sum函数。 sum([1, 2, 3]), sum([Time(1,0,0), Time(0,1,0), Time(0,0,1)])。
+
+
+.. code:: python
+
+ def time_to_seconds(time):
+ minutes = time.hour * 60 + time.minute
+ seconds = minutes * 60 + time.second
+ return seconds
+
+ def seconds_to_time(seconds):
+ time = Time(0, 0, 0)
+ minutes, time.second = divmod(seconds, 60)
+ time.hour, time.minute = divmod(minutes, 60)
+ return time
+ class Time:
+ def __init__(self, h=0, m=0, s=0):
+ self.hour = h
+ self.minute = m
+ self.second = s
+
+ def __add__(self, other):
+ if isinstance(other, Time):
+ return seconds_to_time( time_to_seconds(self) + time_to_seconds(other) )
+ else:
+ return seconds_to_time( time_to_seconds(self) + other )
+
+ def __radd__(self, other):
+ return self.__add__(other)
+
+ def __str__(self):
+ return '%02d:%02d:%02d' % (self.hour, self.minute, self.second)
+
+
+ print(sum([Time(1,0,30), Time(0,0,30), Time(0,59,0)]))
+
+
+
+继承(inheritance)
+``````````````````````````````````````````````````
+
+继承父类中的属性与方法。
+
+.. code:: python
+
+ class A:
+ def __init__(self, a):
+ self.a = a
+ def __str__(self):
+ return 'Parent string method.'
+
+ class B(A):
+ pass
+
+
+ class C(A):
+ def __init__(self, a, b):
+ super().__init__(a)
+ self.b = b
+
+
+ x = B(2)
+ print(x)
+ y = C(2, 3)
+ print(y)
+
+
+扑克牌。Card, Deck, Hand(Deck)。
web 应用程序
````````````
-输入文本
+在文本框输入文本
``````````````````````````````````````````````````
school.py
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