Just released: Delphi Event-based and Asynchronous Programming - Complete version - 291 Pages

-

 Delphi Event-based and Asynchronous Programming





Event-based programming is everywhere. Nowadays, you can hardly write any kind of application without leaning on events and messages.

This simple, yet extremely powerful mechanism is also the cornerstone of asynchronous and multithreaded programming. Without events, we would not know when some task was completed.

But, asynchronous and multithreaded programming consists of more than just handling multiple threads, protecting shared resources, and synchronization. It also includes designing and understanding program flow. That design aspect is often forgotten, taken for granted, and solving all the fine-grained nuances of multithreaded programming hogs the spotlight.

Without understanding asynchronous flow and the bigger picture it can be hard to properly solve all the other issues, including multithreading. What used to be plain spaghetti code, now becomes temporal spaghetti.

You can lose control over your objects, have bits of code creating and releasing them all over the place, even without adding multithreading into the mix. Memory leaks, crashes, and holding references to dead data long after its destruction are perfectly possible even in a single-threaded environment.

While the starting point of this book is giving a proper introduction to event-based and asynchronous programming flow and design, it also provides the necessary implementation details, explanations and code examples needed to put those designs into practice.


 

Table of Contents

Introduction

1. The Loop

Hidden complexity
Peeking at the console
Main event loop
Event-based programming
Pushmi-pullyu
Game loop

2. Messaging Systems

Windows messaging system
Windows messaging system in VCL
Custom messaging systems and patterns
System.Messaging

3. Life, the Universe, and Everything

Life, the Universe, and Everything
Automatic memory management
Interfaces
Class helpers
Anonymous methods and lambdas

4. Asynchronous Programming and Multithreading

Asynchronous programming and multithreading
Making the first dive...
Application.ProcessMessages
Application.ProcessMessages reentrancy problem
Moving long operations to a background thread
Asynchronous message dialog
Tasks
Futures

5. Thread Safety

What is thread safety anyway?
The importance of thread safety
Achieving thread safety
Avoiding shared data
Protecting shared data

6. GUI and Multithreading

Main (GUI) thread
Communicating with the main thread
Communication and GUI issues

Comments

Post a Comment

Popular posts from this blog

Catch Me If You Can - Part II

-
It has been quite some time since I wrote the Catch Me If You Can post about the inability of LLVM-backed compilers to catch non-call hardware exceptions. In other words, hardware exceptions raised by code written in the same block as the try...except exception handler. Since then, more LLVM-backed compilers have been added to Delphi, and with those, more reasons to change common coding practices... but still, very few developers know about the issue. The original article covered only try...except exception handlers, and exploring what exactly happens with implicit and explicit try...finally handlers was left as an exercise to the readers and to some future, now long overdue, post. And Now: All Hell Breaks Loose When you read about non-call hardware exceptions not being caught by an immediate try...except block, the implications might not look too serious. After all, while plenty of code can raise exceptions, try...except handlers are not that frequently used in places, as mo
Read more

Delphi 12.1 & New Quality Portal Released

-
Image
The Delphi 12.1 update has been released. Besides a number of bug fixes, this release also has a few new features. The most notable ones are the new Split Editor, which allows having multiple files opened side by side; and support for Android API 34. You can find more information about what is new in this update at https://docwiki.embarcadero.com/RADStudio/Athens/en/12_Athens_-_Release_1 However, the greatest change for all Delphi developers is a new bug tracking portal that replaces the old one, still available in read-only mode at https://quality.embarcadero.com/ . The new portal is hosted in Atlassian Cloud https://embt.atlassian.net/servicedesk/customer/portals  or through a redirect https://qp.embarcadero.com and is based on Jira Service Management (JSM), while the internal bug tracking system, which was also migrated to the cloud, was not changed and is running on Jira. This move to the cloud was inevitable, because Atlassian retired their Server line of products. JSM is a
Read more

Coming in Delphi 12: Disabled Floating-Point Exceptions

-
Delphi 12 is in the works. One of its small features that will have a huge impact is a change in the default handling of floating-point exceptions, which will now be masked on all platforms. Previously, floating-point exception handling was different across platforms, and most notably on the Windows platform: In VCL and console applications, floating-point exceptions were not masked and would raise an exception. On the other hand, FireMonkey applications had all floating-exceptions masked by default, regardless of which platform they were running on. Basically if you haven't explicitly changed the exception mask in your code to some value other than the default, and you had code that attempted to divide some number with zero, you would get an EZeroDivide exception in previous Delphi versions on the Windows VCL application. In Delphi 12, there is no exception, and the result of such a division will be +INF . So the following code will no longer raise an exception. If you were r
Read more