DS&A

Exercises: Box-and-Pointer Diagrams

Before attempting these exercises, you should view the box-and-pointer diagrams video lecture.

The following classes are defined:

class Foo:
    def __init__(self, baz, qux):
        self.baz = baz
        self.qux = qux

class Bar:
    def __init__(self, quux, quuz):
        self.quux = quux
        self.quuz = quuz

In each of the exercises below, your box-and-pointer diagrams should show the program state after the code has been executed, including all variables, objects, and references.

Exercises

1. Draw a box-and-pointer diagram showing the program state after the following Python code has been executed:

   corge = Foo(1, 2)
   grault = Foo(3, 4)
   garply = Bar(corge, grault)

   
   
2. Draw a box-and-pointer diagram showing the program state after the following Python code has been executed:

   waldo = Foo(5, 6)
   fred = waldo
   fred.baz = 7

   
   
3. Draw a box-and-pointer diagram showing the program state after the following Python code has been executed:

   plugh = Foo(8, 9)
   xyzzy = Bar(plugh, None)
   thud = Bar(xyzzy, xyzzy)

   
   
4. Draw a box-and-pointer diagram showing the program state after the following Python code has been executed:

   wibble = Foo(1, 2)
   wibble = Foo(3, 4)
   wibble = Foo(5, 6)

   
   
5. Draw a box-and-pointer diagram showing the program state after the following Python code has been executed:

   wobble = Bar(None, None)
   wobble = Bar(wobble, None)
   wobble.quuz = wobble

• Tags: 
• exercises, box-and-pointer diagrams, objects, pointers