Design Patterns:Elements of Rousable Object-Oriented Software Preface to CD As we were writing Design Patterns,we knew the patterns we weredescribing had value because they had proven themselves in manydifferent contexts.Our hope was that other software engineers wouldbenefit from these patterns as much as we had. Now,three years after its debut,we find ourselves both grateful andthrilled by how the book has been received.Lots of people use it.Many tell us the patterns have helped them desigr and build bettersystems.Many others have been inspired to write their own patterns,and the pool of patterns is growing.And many have commented on whatmight be improved about the book and what they would like to see inthe future. A recurring comment in all the feedback has been how well-suited thebook is to hypertext.There are numerous crosseferences,andchasing referencesis something a computer can do very well.Sincemuch of the software development process takes place on computers,itwould be natural to have a book like ours as an on-line resource.Observations like these got us excited about the potential of thismedium.So when Mike Hendrickson approached us about turning the bookinto a CD-ROM,we jumped at the chance. two years and several egabytes oflater,ve're delighted thatyou can finally obtain this edition,the Design Patterns CD,and put its unique capabilities to work.Now you can access a patternfrom your computer even when someone has borrowed your book.You can search the text for key words and phrases.It's also considerably easier to incorporate parts of it in your own on-line documentation.And if you travel with a notebook computer,you can keep the bookhandy without lugging an extra two pounds of paper Hypertext is a relatively new publishing venue,one we arelearning to use just like everyone else.If you have ideas on howto improve this edition,please send them todesign-patterns-cdecs.uiuc.edu.If you have questions or suggestions concerning the patternsthemselves,send them to thegang-of-4-patternsecs.uluc.edumailing list.(To subscribe,send e-mail to gang-of-4-patterns@cs.uiuc.eduwith the subject"su e".)This list as quite a few readers,and many of them can answer questions as well as we can-andusually a lot faster!Also,be sure to check out thepatterns Home Page athttp://hillside.net/patterna/.There you'll find other books and mailing lista on patterns,notto mention conference information and patterns published on-line. cecand eaon vork ee ison-Wesley for theiron-going encourageme and support.Jeft Helgesen,Jason Jones,andDaniel Savarese garner many thanks 5Design Patterns: Elements of Reusable Object-Oriented Software 5 Preface to CD As we were writing Design Patterns, we knew the patterns we weredescribing had value because they had proven themselves in manydifferent contexts. Our hope was that other software engineers wouldbenefit from these patterns as much as we had. Now, three years after its debut, we find ourselves both grateful andthrilled by how the book has been received. Lots of people use it.Many tell us the patterns have helped them design and build bettersystems. Many others have been inspired to write their own patterns,and the pool of patterns is growing. And many have commented on whatmight be improved about the book and what they would like to see inthe future. A recurring comment in all the feedback has been how well-suited thebook is to hypertext. There are numerous cross-references, andchasing references is something a computer can do very well. Sincemuch of the software development process takes place on computers, itwould be natural to have a book like ours as an on-line resource.Observations like these got us excited about the potential of thismedium. So when Mike Hendrickson approached us about turning the bookinto a CD-ROM, we jumped at the chance. Two years and several megabytes of e-mail later, we're delighted thatyou can finally obtain this edition, the Design Patterns CD,and put its unique capabilities to work. Now you can access a patternfrom your computer even when someone has borrowed your book. You can search the text for key words and phrases. It's also considerably easier to incorporate parts of it in your own on-line documentation.And if you travel with a notebook computer, you can keep the bookhandy without lugging an extra two pounds of paper. Hypertext is a relatively new publishing venue, one we arelearning to use just like everyone else. If you have ideas on howto improve this edition, please send them todesign-patterns-cd@cs.uiuc.edu.If you have questions or suggestions concerning the patternsthemselves, send them to thegang-of-4-patterns@cs.uiuc.edumailing list. (To subscribe, send e-mail to gang-of-4-patterns@cs.uiuc.eduwith the subject "subscribe".) This list has quite a few readers, and many of them can answer questions as well as we can—andusually a lot faster! Also, be sure to check out thePatterns Home Page athttp://hillside.net/patterns/.There you'll find other books and mailing lists on patterns, notto mention conference information and patterns published on-line. This CD entailed considerable design and implementation work. We areindebted to Mike Hendrickson and the team at Addison-Wesley for theiron-going encouragement and support. Jeff Helgesen, Jason Jones, andDaniel Savarese garner many thanks