Book Image

Hands-On Design Patterns with Delphi

By : Primož Gabrijelčič
Book Image

Hands-On Design Patterns with Delphi

By: Primož Gabrijelčič

Overview of this book

Design patterns have proven to be the go-to solution for many common programming scenarios. This book focuses on design patterns applied to the Delphi language. The book will provide you with insights into the language and its capabilities of a runtime library. You'll start by exploring a variety of design patterns and understanding them through real-world examples. This will entail a short explanation of the concept of design patterns and the original set of the 'Gang of Four' patterns, which will help you in structuring your designs efficiently. Next, you'll cover the most important 'anti-patterns' (essentially bad software development practices) to aid you in steering clear of problems during programming. You'll then learn about the eight most important patterns for each creational, structural, and behavioral type. After this, you'll be introduced to the concept of 'concurrency' patterns, which are design patterns specifically related to multithreading and parallel computation. These will enable you to develop and improve an interface between items and harmonize shared memories within threads. Toward the concluding chapters, you'll explore design patterns specific to program design and other categories of patterns that do not fall under the 'design' umbrella. By the end of this book, you'll be able to address common design problems encountered while developing applications and feel confident while building scalable projects.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
About Packt


Fixing bugs in a complex program can be a complicated task. Sometimes, bugs are straighforward, while others are hard to reproduce or fall into the "there's no way that the current code produces this result" area.

A good programmer doesn't use random changes to the code to fix problems but approaches debugging methodically. Different people use different debugging approaches, but they can be typically summarized in the following steps:

  1. Gather the data.
  2. Develop a hypothesis.
  3. Test the hypothesis.
  4. Repeat until the test succeeds.
  5. Add a test to the unit tests.

The last step (regression testing) is especially important as it prevents the bug to be accidentally reentered into the code by merging the incorrect version of the source.

To really fix a bug, you have to reproduce it first. Fixing a bug that you can't repeat is just performing guesswork. Your fix may work, or it may not, and even if it works, you won't know whether your changes really fixed the bug or whether it is not reappearing for...