more work with oop

KitN · KitN · commit 84ceac675218 · 2022-04-04T11:38:19.000+08:00
diff --git a/code/BadKangaroo.py b/code/BadKangaroo.py
@@ -29,7 +29,7 @@ def __init__(self, name, contents=[]):
         contents: initial pouch contents.
         """
         self.name = name
-        self.pouch_contents = contents
+        self.pouch_contents = [i for i in contents]
 
     def __str__(self):
         """Return a string representaion of this Kangaroo.
@@ -45,6 +45,7 @@ def put_in_pouch(self, item):
 
         item: object to be added
         """
+        print(f'Adding {item} to a pouch') 
         self.pouch_contents.append(item)
 
 
@@ -55,6 +56,7 @@ def put_in_pouch(self, item):
 kanga.put_in_pouch(roo)
 
 print(kanga)
+print(roo)
 
 # If you run this program as is, it seems to work.
 # To see the problem, trying printing roo.
diff --git a/exersizes/Kangaroo.py b/exersizes/Kangaroo.py
@@ -0,0 +1,23 @@
+# For ThinkPython Chapter 17 Exersize 2
+
+class Kangaroo():
+    def __init__(self):
+        self.pouch_contents = []
+
+    def __str__(self):
+        return "Pouch: " + str(self.pouch_contents)
+
+    def put_in_pouch(self, thing):
+        self.pouch_contents += [thing]
+
+
+def main():
+    kanga = Kangaroo()
+    roo = Kangaroo()
+    roo.put_in_pouch('skittle')
+    kanga.put_in_pouch(roo)
+    print(kanga)
+    print(roo)
+
+if __name__=='__main__':
+    main()
diff --git a/exersizes/Time2.py b/exersizes/Time2.py
@@ -0,0 +1,124 @@
+"""This module contains a code example related to
+
+Think Python, 2nd Edition
+by Allen Downey
+http://thinkpython2.com
+
+Copyright 2015 Allen Downey
+
+License: http://creativecommons.org/licenses/by/4.0/
+"""
+
+from __future__ import print_function, division
+
+
+class Time:
+    """Represents the time of day.
+       
+    attributes: hour, minute, second
+    """
+    def __init__(self, hour=0, minute=0, second=0):
+        """Initializes a time object.
+
+        seconds: int of seconds since midnight
+        """
+        self.seconds = 0
+        self.seconds += hour*60*60
+        self.seconds += minute*60
+        self.seconds += second
+
+    def __str__(self):
+        """Returns a string representation of the time."""
+        second = self.seconds % 60
+        minute = self.seconds % 3600 // 60
+        hour = self.seconds // 3600
+        return '%.2d:%.2d:%.2d' % (hour, minute, second)
+
+    def print_time(self):
+        """Prints a string representation of the time."""
+        print(str(self))
+
+    def time_to_int(self):
+        """Computes the number of seconds since midnight."""
+        return self.seconds
+
+    def is_after(self, other):
+        """Returns True if t1 is after t2; false otherwise."""
+        return self.time_to_int() > other.time_to_int()
+
+    def __add__(self, other):
+        """Adds two Time objects or a Time object and a number.
+
+        other: Time object or number of seconds
+        """
+        if isinstance(other, Time):
+            return self.add_time(other)
+        else:
+            return self.increment(other)
+
+    def __radd__(self, other):
+        """Adds two Time objects or a Time object and a number."""
+        return self.__add__(other)
+
+    def add_time(self, other):
+        """Adds two time objects."""
+        assert self.is_valid() and other.is_valid()
+        seconds = self.time_to_int() + other.time_to_int()
+        return int_to_time(seconds)
+
+    def increment(self, seconds):
+        """Returns a new Time that is the sum of this time and seconds."""
+        seconds += self.time_to_int()
+        return int_to_time(seconds)
+
+    def is_valid(self):
+        """Checks whether a Time object satisfies the invariants."""
+        midnight = 24*60*60
+        if self.seconds < 0:
+            return False
+        if self.seconds >= midnight:
+            return False
+        return True
+
+
+def int_to_time(seconds):
+    """Makes a new Time object.
+
+    seconds: int seconds since midnight.
+    """
+    minutes, second = divmod(seconds, 60)
+    hour, minute = divmod(minutes, 60)
+    time = Time(hour, minute, second)
+    return time
+
+
+def main():
+    start = Time(9, 45, 00)
+    start.print_time()
+
+    end = start.increment(1337)
+    #end = start.increment(1337, 460)
+    end.print_time()
+
+    print('Is end after start?')
+    print(end.is_after(start))
+
+    print('Using __str__')
+    print(start, end)
+
+    start = Time(9, 45)
+    duration = Time(1, 35)
+    print(start + duration)
+    print(start + 1337)
+    print(1337 + start)
+
+    print('Example of polymorphism')
+    t1 = Time(7, 43)
+    t2 = Time(7, 41)
+    t3 = Time(7, 37)
+    total = sum([t1, t2, t3])
+    print(total)
+
+
+if __name__ == '__main__':
+    main()
