Special

Introducing the “Welcome to Xojo” Bundle!

New to Xojo and looking for guidance? We've put together a terrific bundle to welcome you! Xojo Bundle

This bundle includes six back issues of the magazine -- all of year 21 in printed book and digital formats -- plus a one-year subscription (beginning with 22.1) so you'll be learning all about Xojo for the next year. It's the perfect way to get started programming with Xojo. And you save as much as $35 over the non-bundle price!

This offer is only available for a limited time as supplies are limited, so hurry today and order this special bundle before the offer goes away!

Article Preview


Buy Now

Issue 2.4

COLUMN

Return Type Covariance

Issue: 2.4 (March/April 2004)
Author: Charles Yeomans
Author Bio: Charles Yeomans pontificates on REALbasic from Lexington, Kentucky.
Article Description: No description available.
Article Length (in bytes): 5,311
Starting Page Number: 36
Article Number: 2417
Related Link(s): None

Excerpt of article text...

REALbasic 5.5 adds a new language feature, return type covariance. Despite the technical name, it's easy to grasp by seeing it in use. So let's begin by seeing how return type covariance solves a problem.

The Factory Method Pattern

...End of Excerpt. Please purchase the magazine to read the full article.