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


The future pattern, also known as a promise, can be simply described as a function that runs in the background thread. The basic usage pattern is intentionally very simple:

  • The main thread creates a future (starts a calculation in another thread).
  • The main thread does some other work.
  • The main thread reads the result of the future (reads the result of the calculation). If the calculation is not finished yet, the main thread blocks until the result is available.

The future pattern allows the program to execute multiple tasks in parallel while it neatly encapsulates the background calculation in a separate function. It also provides a simple way of re-synchronization between two threads when the result of calculation is required.


In a kitchen, the chef asks their assistant to cut up a few onions. While the assistant peels, cuts, and cries, the chef continues preparing other meals. At a later time, when they need to use the onion, it will hopefully be already prepared and waiting.