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

Template method

A template method (sometimes just called a template) is a design pattern that defines a template for an algorithm. Instead of coding a full, working solution, a template method implements just the important parts and leaves some details unfinished. It is up to the derived subclasses to implement the missing parts and through that, provide a working algorithm.


A recipe in a cookbook represents a template method. It may say something  like take three cups of flour (without specifying where exactly you should get this flour from), put into the oven (without specifying exactly which of your baking tins you should use and what specific mark of oven that should be), serve when cold (without providing any detail about serving plates and table setting), and so on.

As defined by the Gang of Four, the template method implements the important part of the algorithm (the business logic) and leaves concrete details unfinished. Usually, they are implemented as a set of abstract methods...