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
Contributors
Preface
Index

Exceptions


Exceptions are mechanisms that bypass normal program execution flow. Although the specific details are language-specific, many modern programming languages follow the same principles.

A piece of code may signal invalid condition by raising an exception. (This is also called throwing an exception.) This exception may be a hardware exception that's generated in the hardware (on the CPU) or a software exception that's generated in the code.

 

Typical examples of hardware exceptions are access violations (where a program tries to access an invalid memory location) and division by zero. Software exceptions are more diverse, as they are frequently raised in different places of the Delphi runtime library. Probably the most well-known of all is the range check error exception, which is raised when the code, tries to access elements of a list that don't exist.

When an exception is raised, the code immediately exits from the current method, its caller, the caller's caller, and so on until it...