Data Structures and Algorithms with Object-Oriented Design Patterns in Python

Exercises

Specify the set of values and the set of operations provided by each of the following Python types:
1. int,
2. float, and
3. str.
What are the features of Python that facilitate the creation of user-defined data types.
Explain how each of the following Python features supports polymorphism:
1. classes,
2. inheritance, and
3. special methods like __cmp__ and __ismember__.
Suppose we define two concrete classes, A and B, both of which are derived from the abstract Object class declared in Program . Furthermore, let a and b be instances of classes A and B (respectively) declared as follows:
```
class A(Object):
    ...
class B(Object):
    ...
a = A()
b = B()
```
Give the sequence of methods called in order to evaluate a comparison such as ``a < b''. Is the result of the comparison True or False? Explain.
Let c be an instance of some concrete class derived from the Container class given in Program . Explain how the statement
```
print str(c)
```
prints the contents of the container on the console.
Suppose we have a container c (i.e., an instance of some concrete class derived from the Container class defined in Program ) which among other things happens to contain itself. What happens when we invoke the __str__ method on c?
Iterators and visitors provide two ways to do the same thing--to visit one-by-one all the objects in a container. Give an implementation for the accept method of the Container class that uses an iterator.
Is it possible to implement an iterator using a visitor? Explain.
Suppose we have a container which we know contains only plain integers. Design a Visitor which computes the sum of all the integers in the container.
Consider the following pair of Associations:
```
a = Association(3, 4)
b = Association(3)
```
Give the sequence of methods called in order to evaluate a comparison such as ``a == b''. Is the result of the comparison True or False? Explain.