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D Cookbook

You're reading from   D Cookbook Discover the advantages of programming in D with over 100 incredibly effective recipes with this book and ebook.

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Product type Paperback
Published in May 2014
Publisher
ISBN-13 9781783287215
Length 362 pages
Edition Edition
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Author (1):
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Adam Ruppe Adam Ruppe
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Adam Ruppe
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Table of Contents (21) Chapters Close

D Cookbook
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Core Tasks FREE CHAPTER Phobos – The Standard Library Ranges Integration Resource Management Wrapped Types Correctness Checking Reflection Code Generation Multitasking D for Kernel Coding Web and GUI Programming Addendum Index

Using scope guards to manage transactions


D doesn't require you to make wrapper types or write try/catch statements all the time. You can also use scope guards. They can be triggered by three conditions: exit, success, or failure. Here, we'll perform a multistep transaction with scope guards to ensure exception safety.

How to do it…

In order to use scope guards to manage transactions, perform the following steps:

  1. Begin your transaction.

  2. Write a scope(success) guard to commit the transaction immediately after starting it (if committing isn't implicit).

  3. Write a scope(failure) guard to roll back the transaction immediately after starting it. You may use multiple blocks to rollback multiple steps.

  4. Write a scope(exit) guard to free any resources. Write the free code immediately after the acquisition code. You may use multiple blocks to free multiple resources.

  5. Write the following code for your transaction:

    {
      // performing a SQL transaction
      database.query("START TRANSACTION");
      scope(success) database...
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