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

Form inheritance

Delphi is an object-oriented language and it is no wonder that objects and inheritance are used throughout the runtime libraries. That includes both user interface frameworks, VCL and FireMonkey, where every user interface element from a label to a form is represented as an object.

It is no big surprise that we can use the object-oriented approach to create new user interface elements by deriving from existing ones. As each form is represented with its own class (usually inheriting from TForm), we can even use inheritance to create new forms. Even more, the IDE implements tooling support for creating inherited forms and maintaining the repository of base forms.


Chapter 5, Adapter, Proxy, Decorator, and Facade, discusses how inheritance can be used to create a proxy object for a button in the Delphi idioms – replacing components in runtime section.

Form inheritance is useful in two common situations. First, it functions great when you need the same functionality in multiple...