Home > Articles > Software Development & Management

Brian Foote on the 15th Anniversary of Design Patterns

Brian Foote shares his thoughts about Design Patterns: Elements of Reusable Object-Oriented Software on the 15th anniversary of its publication.
Like this article? We recommend

InformIT: If you were at the 1994 OOPSLA in Portland where Design Patterns debuted, what are some of your recollections of that show and of the book at the show?

The brave men and women of the Addison-Wesley booth at OOPSLA '94 in Portland had no Internet connection, for those did not yet exist, at least in a form most people would recognize today. Cellphones were few. In October of 1994, cellphones were still largely an affectation for financiers. And they were caught in ... a stampede.

The only thing that seemed to back the horde was a wall of books. Not any book, but a particular newly-released book. They thought they'd come armed with plenty of them. But they were running out of them, fast, and, in desperation, exhaustion, exhilaration, and yes, disbelief, were trying to locate more...

While it wasn't quite Beatlemania, it was the closest thing to it that the likes of OOPLSA would ever see. It was a day that transformed the authors of a seeming arcane catalog of second-hand designs into software superheros. John Vlissides, Ralph Johnson, Richard Helm and Erich Gamma had been transmogrified into Gamma et al., The Gang of Four.

Even the name "Gang of Four" sounded revolutionary, or counter-revolutionary, or a tad subversive, depending on your view of Chinese history during 1970. It was at least what what we now call "disruptive."

Over time, even the moniker "Gang of Four" was abbreviated. Cognoscenti came to glibly refer to Design Patterns: Element of Reusable Object-Oriented Design as the "GoF" (rhymes with "cough") Book. The authors were simply "The GoF."

The Great OOPSLA 1994 Gang of Four Reading Frenzy was unprecedented. Before the show was over, more than 700 copies of the GoF Book had been sold. These would be the first of three nearly half-a-million copies that would be sold, in umpteen languages, over the next fifteen years. To set this number in perspective, bear in mind that some six million souls—about 1 in 1000 Earthlings—makes their living as a software developer.

InformIT: What was your initial reaction to the publication of Design Patterns?

I was a working with one of the authors of Design Patterns those days, Ralph Johnson, and the University of Illinois during the development of the manuscript for this book.

It was a highly collaborative, distributed effort, using email and newsgroups to exchange drafts and solicit what was probably an unprecedented degree of community feedback. This community building effort certainly contributed to both the quality of the resulting book, and to its subsequent heroes' welcome.

I was struck initially by how this effort broke all the rules of scholarship. What was new here was that nothing was new here. Academics were traditionally rewarded for publishing new, original ideas they had thought of themselves. The GoF book was full of old ideas that other people had thought of. It was a catalog filled with stuff that people working with objects, ahem, already knew.

It almost felt like they were cheating. It quickly became obvious that the GoF had slashed the Gordian Knot of Originality, in Computer Science, at least. Naming, describing, and cataloging indigenous accepted wisdom has become, well, not quite orthodox, but at least better accepted in CS than it was prior to the GoF book.

I was also amazed by the unexpected embrace that the idea of patterns as a literary form was to receive. Writing that diverged from the cold, sterile standards of academic journal writing of the time was regarded as ostentation, or as a fig-leaf meant to hide a presumed lack of rigor. The GoF book, and the patterns movement it spawned, helped bring a greater sense of clarity and concern for the reader into vogue in CS.

What I think struck me most was that the patterns book moved the focus back from programming languages and frameworks to the idioms and ideas that experienced programmers were able to express using these media.

InformIT: How has your opinion of the book changed over the last 15 years?

I think the thing that has surprised me the most about the GoF catalog is how well their initial cut on this part of the design space has held up.

We said at the time that we had no idea how many patterns describing the wisdom of the object masters at this level there would be. Dozens more? Hundreds?

Remarkably, this set of twenty-three patterns has held up surprisingly well. There may be another dozen or so patterns that have been subsequently discussed—some variations on patterns in the GoF catalog—that deserve to be mentioned in the same breath as the GoF patterns, but…

The real surprise is that the set that is there has held up so well. I’m reminded of the ancient constellation boundaries we use to map the heavens. Other lines than the established ones were drawn by other cultures, but the lines we know now, once established, the names we now use, resist attempts at revision.

Modern astronomers managed to add a few less mythologically colorful constellations to the ancient mix, but their efforts only underscored the beauty of the ones already set.

So it is with Design Patterns as well.

InformIT: How has Design Patterns changed your impressions about the way software is built?

The vision of reuse that we had in the object-oriented community in hindsight seems like a God that Failed. Just as the Space Shuttle never lived up to its promised reuse potential, libraries, frameworks, and components, while effective in as far as they went, never became foundations of routine software reuse that many had envisioned and hoped.

Instead, designs themselves, design ideas, patterns became the loci of reuse. We craft our ideas, by hand, into each new artifact we build.

We don’t assemble them like Lego blocks.

InformIT: How has Design Patterns impacted the last 15 years of development?

It’s fascinating to look at software written after the GoF book and compare it with software written prior to it. In shops that have been pattern infected, one is struck by the penetration of the GoF ideas, and the GoF vocabulary in the code itself.

That said, working programmers trying to cultivate more lucid, durable code often feel as if they are trying to fight off a lahar with garden tools. Mediocre code is still being produced at a prodigious rate, faster than it can be tamed. Patterns have shown us that better design is possible. But without a commitment to design integrity and sustainable development practices, these benefits can be washed away by burgeoning, unregulated growth and neglect.

The battle between the forces of “slash-and-burn” software agriculture and sustainability still rages, and the outcome remains uncertain.

InformIT: Have you been personally affected by the book? In other words, has it changed the way you think about software development or changed the way you develop software?

The GoF book made the world safer for the idea that software, code, could be better than some of the festering spaghetti code jungles that then, alas, as now, were all to often the product of teams that had never been exposed to the idea that there was any other way.

It reminded us that it was okay to believe that one’s programs could be a source of pride.

InformIT: What is your favorite Pattern (or least favorite Pattern) and why?

When I teach patterns, I’m fond, as the course comes to a close, of asking everyone in it both those questions. The answers I get are all over the map. When I’m done, I like to give an answer too. Mine have varied as well.

In hindsight, perhaps the most influential idea has been one that is not even explicitly in the catalog: the generalized notion of Factory. A Factory is an object that delivers an instance of some Product. This pattern exists in the broad penumbra that surrounds explicit GoF catalog entries such as Factory Method and Abstract Factory. By hiding the details of object creation by allowing Factories to produce products, the constraints and limitations of explicit object construction can be circumvented.

I also became fond of citing the humble Iterator pattern as a personal favorite. Its adoption by the Java community made this idea commonplace. Iterator keeps other objects from depending on how an object organizes its internal data, by supplying an Iterator instead. As such, I think its role in allowing objects to retain their integrity as a system evolves has been underappreciated.

But, I’ve developed a soft spot over the years for the notorious Visitor pattern. I’ve encountered classes where different students have named this pattern as their favorites, while others single it out for scorn.

Visitor may not be the most intricate design in the book, it has earned a reputation as being the hardest GoF “merit badge” to earn. I’ve found that no one, me included, has ever really understood it until they have built one, and that then the design idea was theirs, for good or ill, for life.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020