CS 4448 - Fall 1998
Object-Oriented Programming and Design
Talk 5.2
by
Ryan Fowler

Programming with Generic Interfaces

by

Lowell Kaplan

• Introduction
  First, in order to understand what a generic interface is, we need to define what a non-generic interface is (Listing 1).
  • Get and set methods for every variable.
  
  
  • Everything is laid out neatly.
  
  


• Moving on...
  Now we want to look at a more generic interface (Listing 2).
  • By using a hashtable we can eliminate individual data members.
  
  
  • Now there are only two methods: one for accessing and one for mutating.
  
  
  
  Advantages to this generic interface?
  
  • Code is much smaller.
  
  
  • Only need one member function for each data member.
  
  
  • New attributes can now be added at runtime.
  
  
  
  Disadvantages?
  • Program needs to know the string names of the property to be used.
  
  
  • They could be defined elsewhere, but that nullifies advantage #2.
  
  
  • Loss of information about the properties.
  
  
  • Variable "name" could be set with information for "price".
  
  


• Let's get more generic
  Now let's create a method called "callMethod". It takes a string and an array. The string is the name of the function and the array is the parameter list.
  
  Advantages -
  
  • We've attained a truly generic class.
  
  
  • This would be easy to use for timing purposes.
  
  
  • It could also make debugging code somewhat easier.
  
  
  
  Disadvantages -
  
  • The client must now know the names of the available properties.
  
  
  • There is a loss of compile-time type checking.
  
  
  • There is a significant loss of code readability.
  
  
  
• Conclusions
  1. "Generic interfaces seem best suited for times when objects are likely to change frequently, like during the beginning of a development projects. Once the object's interface becomes more stable, a migration to regular functions may be appropriate."