1 Example: No Explicitly Defined Constructors

We are not referring to the explicit keyword.

A smart aleck on your team has written a class, Cookbook. He has failed to declare a constructor–i.e., he has declared zero constructors. How would you persuade him that an explicitly declared Default constructor is necessary?

• Declare a Cookbook variable
• Declare an array of Cookbooks
• Create a specialized Cookbook–i.e., inherit from Cookbook
• Create function that takes a Cookbook passed by value
• Create function that takes a Cookbook passed by reference
• Add a constant data member to CookBook
• Ask which data structure he used

Let us individually examine each of these.

• Declare an array of Cookbooks

  Cookbook cookbooks[10];
  

  or

  Cookbook* cookbooks = new Cookbook[10];
  

• Declare a Cookbook variable

  Cookbook cookbook;
  

• Create a specialized Cookbook–i.e., inherit from Cookbook

  class SimpleCookbook : Cookbook {
      // Some code
      // ...
  };
  

• Create function that takes a Cookbook passed by reference

  bool teachMeToCook(Cookbook &manual);
  

• Add a constant data member to CookBook

  class Cookbook {
      private:
          const int something;
  
      // original code
      // ...
  };
  

• Ask which data structure he used–e.g.,

  • vector<Recipe>
  • vector<Recipe*>
  • Linked List
  • Array

2 UML: Relationship & Association Review

How would I represent the following in UML?

1. A Course may be offered in multiple Section-s.

    
   

2. A Section is composed of Student-s.

    
   

3. Course-s may have linked Recitation-s and Lab-s.

    
   

4. Student-s may be required to enroll in one Lecture, one Lab, and one Recitation for a given Course.

   This is not a relationship that can be meaningfully captured with UML class diagrams. This scenario is more suited for UML Sequence diagrams. This type of scenario will not be present on the Midterm Exam.

3 Questions to Consider

3.1 Coding

1. When do I need to implement the Big-3?
   1. What is shallow copy?
   2. What is deep copy?
2. What is const-correctness?
3. If I define operator<< or operator>> as member functions, what am I defining?
4. What variable types allow me to make use of inheritance?
   1. value-type?
   2. reference-type?
   3. pointer-type?

3.2 Design

1. Object-oriented analysis and design is useful even if a program will not be written in an Object Oriented programming language.

2. When do I need index cards?

   • What am I creating?
   • In which phase of design am I currently engaged?

3. Initial Design with CRC cards UML Class diagrams

   • Assigning Responsibilities.
   • Listing Collaborators.
   • The A-B-C Rule.

4. What is inheritance?

   • How do I represent inheritance in UML Class diagrams?
   • What is the name of this association?

5. What are aggregation and composition?

   • How do I represent aggregation in UML?
   • How do I represent composition in UML?
   • How are aggregation and composition different?

3.3 Cross-Language Class Checklist Rules

Consider our class checklist discussion, specifically the comparison of C++, Java and Python 3.