'Design Patterns' Receives ACM SIGPLAN Award

bth writes "ACM's Special Interest Group on Programming Languages (SIGPLAN) recently awarded the 2005 Programming Languages Achievement Award to Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides (known as the 'Gang of Four') for their creation of 'Design Patterns' (the computer science book and the subfield at the intersection of programming languages and software engineering). The annual award recognizes an individual (or individuals) who has (have) made a significant and lasting contribution to the field of programming languages."

Comments

As mentioned by Paul Graham

[putko]

As mentioned by Paul Graham, in his essay "Revenge of the Nerds", Peter Norvig found that 16 of the 23 patterns in Design Patterns were "invisible or simpler" in Lisp.

Re:As mentioned by Paul Graham

[whatthef*ck]

As mentioned by Paul Graham, in his essay "Revenge of the Nerds", Peter Norvig found that 16 of the 23 patterns in Design Patterns were "invisible or simpler" in Lisp.

If I could make a decent living coding in Lisp, I might actually give a shit.

Re:As mentioned by Paul Graham

[shmlco]

I just can't help myself given that sentence. To quote, "Language bigots always think they're language is perfect."

Yes, language bigots always think THEY ARE language is perfect.

Re:As mentioned by Paul Graham

[be-fan]

You're right, design patterns aren't duplicated code. They're duplicated patterns of code. Nearly all languages have a tool for handling duplicated code (functions), but few have tools to handle duplicated patterns of code. Lisp macros, however, do allow you to codify patterns in code.

Lisp macros and C macros share only a name. The C preprocessor is just a simple text-substitution mechanism. In comparison, Lisp macros are functions that take source code as input, and return source code as output. They have all the generality of regular functions, except the compiler invokes them at compile-time to expand calls.

The simplest examples of Lisp macros are defining new control structures. For example, Lisp has no direct equivalent of Python's "for elt in container" syntax. However, it's easy to write a macro that takes the statement (for (x in list) ...)" and expands it to an iteration using Lisp's native 'do' loop. Now, that's just scratching the surface of macros. Since macros are just functions, you can do anything with them, including writing a language on top of Lisp. This might seem like a bit of a strange idea, but domain-specific languages are hardly a new concept (ie: SQL), and its easier to build them on top of a mature platform instead of writing your own compiler.

With regards to macros and patterns, an easy way to think about things is to realize that functions are useful when you need to apply the same code to different data, while macros are useful when you need to apply the same structure to different code. The classical idea is that you can't package up design patterns into a library. That's because few languages have macros (ie: functions that operate on source code). When you have such a feature, packaging up design patterns becomes easy. Just codify the invariant parts into the macro, and put the parts of the code that change as parameters to the macro. If you've read Alexanderescu's book "Modern C++ Design", you'll see that this is precisely what he does with C++ templates (which are a limited and kludgy form of macros). This is big news in the C++ world, for the simple reason that it makes code less tedious to write and less error prone.

terminology, methods, what?

[Rubel]

I've worked with a couple of folks who swore by this book, but I never really heard much from them about why. Is it about good algorithms? Or larger design issues (such as)?

Or is it more about just giving programmers a common vocabulary with which to discuss the way they bulid software?

Is it good reading for an amatuer programmer, or more as an advanced topic?

Re:terminology, methods, what?

[smittyoneeach]

It serves as a common language for designers to talk about what they're doing.
It gives standard terminology for talking about, among other things, how you'd implement an undo function in an application.
However, such standardization flies in the face of the need to re-invent the wheel and sell it as a shiny new technology.

Re:terminology, methods, what?

[fermion]

I think it is about idioms. There are standard ways to copy, iterate, and count. These standard not only make the code more readable, but also provides time tested methods to make the code reliable. Also using these idioms when writing code speeds up the process. There was a time when I could at sketch out a solution to a moderately complex problem in a day, flesh it out in another day or two, and then spend the rest of the time debugging and clarifying.

When we moved to OOP, new idioms were needed. We kept many of the old ones, and the OOP made complying with some rules, such as the separation of data, presentations, and manipulation, simpler. This is what design patterns does. It provides a set of idioms that can be applied to classes of problems. Once these are learned, one should be able to quickly develop a robust solution.

Take for example the singlet. It is a simple construct used when only one instance of an object is allowed. This happens more than one might imagine. I could sit down and think hard for a while and implement singlet, and then redesign, and debug, and after months of work come up with a good solution. Or I could just use the design pattern and in 20 minutes implement my singlet class.

The second part of you question is more complex. I, like most programmer, created crude versions of the design patterns on my own before reading this book. I even saw I enforced some OO concepts on my structured programming. Once I read the book I quickly saw the uefulness and began to use the patterns in my professional work. OTOH, when I was coding some math stuff over the summer, I did not use the patterns because the work was not so suited to the patterns. If i were to publish the work, I might go back and rework to fit the idiom. OTOH I know that the book is used widely and knowing the basics are useful. So if you are coding for fun, it might not help that much. If you are coding to show others, it would help to put the code in a form people will recognize.

Well deserved

[Sv-Manowar]

Its good to see these people being recognized for contributing such a useful concept to object oriented programmers, and its wholly appropriate they should recieve such an award from a group focused on exploring "implementation and efficient use" of programming languages. Although they have their critics, Design patterns have surely helped many programmers greatly in this manner, especially in languages such as java.

For OO fans...

[William Robinson]

This site is one of the best.

Oh dear...

[groman]

Oh my

The quite possibly most useless book in the history of computer science gets an award. Somehow I am not that surprised, considering that everybody hails it as the end all of object oriented design and everything.

To be honest, modern computer science curriculum seems to be wasting a lot of bright young potential on buzzwords. Patterns, paradigms, bleh. People somehow manage to get masters degrees in CS from Berkeley without even knowing what "turing complete", "Karnaugh map", "Rice's theorem", "Goedel's completeness theorem", "planar graph", "functional language", "church-turing thesis" are. But you ask them about a singleton, model-view controller or Java's security model in reflection and they're the fucking expert.

Well that's barely computer science, that's just OO banging. Just because it uses paradigms and object oriented terms doesn't make it anything other than advanced code banging.

Re:Oh dear...

[Anonymous Coward]

Of course it isn't Computer Science, it is Software Engineering. The book helps you design software systems. Can Karnaugh maps do that?

I find it useful with what I work on. If you don't then, maybe the book just isn't for your line of work.

Design patterns are a tool, not a silver bullet. Get what you can out of them but don't be surprised when doesn't solve all the problems in the world.

Re:Oh dear...

[cratermoon]

People with CS degrees seem to get jobs writing software for money without knowing a thing about security, testing, defect discovery and removal, team organization, refactoring, design, technical writing, communication, estimating, abstractions and complexity management, business practices, communicating with users... well, anything needed to actually deliver working software that delivers value to the business.

But, you know, in case that trucking company struggling with logistics needs to know about "turing complete", "Karnaugh map", "Rice's theorem", "Goedel's completeness theorem", "planar graph", "functional language", "church-turing thesis", they're golden.

Re:Oh dear...

[SirSlud]

Face it; software is now a commodity business. Using an automotive analogy, if you want to improve the performance or design of the internal combustion engine, go for it, but most software jobs these days only requires putting a kit together rather than having to push the envelope of science.

Therefore, sure, Computer Science is science, but understand that its pure semantics. Its good that enrollment in CS is down, because most of the CS students during the boom were more interested in engineering (applying known scientific discoveries) than the science itself.

The fact that employers looking for programmers ask for CS degrees is simply an indication that the industry is still fairly young. Software engineers used to come out of CS, but that trend is rightfully dwindling. Most programmers really should be trained in an engineering course, where the focus on economics and social responsibility are more pronounced.

Re:Oh dear...

[Anthony Liguori]

People somehow manage to get masters degrees in CS from Berkeley without even knowing what "turing complete", "Karnaugh map", "Rice's theorem", "Goedel's completeness theorem", "planar graph", "functional language", "church-turing thesis" are.

You're obviously trying to come off as pompus but seriously, do you even really know what you're talking about? What's so important about Karnaugh maps? It's a silly way as solving a system of boolean alegbra equations. Only really useful for introduction digital circuit design.

If you want to talk about boolean logic, talk about predicate calculus, modus ponus, or something that actually deals with Computer Science theory.

I understand where you're coming from and don't fully disagree but you sound like an ass. There's always someone with a more theoritical background than you so just don't do that.

FWIW, the GoF are important because they were the *first* to do what they did--give programmers a common vocabularily to describe complex systems.

Excellent material, often taught incorrectly

[bsandersen]

Congratulations to the GoF. Their observations of patterns of systems and behavior are well-described and well-cataloged in their book. I only wish the concepts and materials were conveyed better when taught.

Most of the time people start with the attitude "Let's start with the Visitor pattern" or something like that. The point of the patterns movement is there are common things that are done, wouldn't it be nice if we could talk about them with common terminology and use the full richness of our experience to ensure when we see the problem again that we don't make all the same mistakes we made last time.

I'd like to see it taught (and this can be in the programming shop, too) like this: "What are we trying to do? Where have we done something like this before? Doesn't this look like something we've done last month? Can you detect a pattern to all this?!"

Instead, what I often see if people spouting pattern names like one would name-drop at a party--the more you drop the more important you must be. Starting with the problem to be solved, the understanding of same, and then recognizing that we've seen this before, then naming the pattern is less flashy but is more the intent of the GoF IMHO.

worth it for one reason

[bmac]

The patterns themselves are not really that
groundbreaking, IMO; the genius of the book
is the perspective on looking at software
as pattern definitions and then their use
in different ways and places in software.

The part that every OO developer should
ingrain in their brain is to

Prefer composition to inheritance.

Good Lord, people love their inheritance
when there are very, very rare situations
that call for it. (Composition, btw, is
where a data structure is used as a data
member of the class).

What it recommends is that instead of this:

class cElement : cParent { ... }

use this:

class cElement {
      cParent mParent; ...
}

Inheritance is so friggin abused by OO
developers, it is ridiculous.

So, my recommendation is to read the first
50 pages or so, which is their general
perspective on programming. After that,
it's just details about the patterns they
have encountered in their careers.

Peace & Blessings,
bmac

An observation...

[bunyip]

"Some is good, more is better, and too much is just about right."

- This mantra is good for money, horsepower, disk space, but not design patterns...

When somebody starts telling me that they used 5 different patterns in their program and they're proud of it - then I know the code is crap. Most of the pattern zealots I've seen write bloated, inefficient code. Sometimes I think they scour the literature looking for some extra patterns to put in.

That said, these patterns do exist and programmers keep reinventing them. The key is knowing when to call it a pattern and go to the trouble of formalizing it versus just writing code. Alternatively, find a language that makes most of these go away.

Easily mastering design patterns

[De Lemming]

The classic Design Patterns book is great, and the GOF certainly deserves this award. Still, the book is hard to read. And in daily practice, it's not always clear when to apply which pattern (especially for the less experienced).

I'm reading Head First Design Patterns, published by O'Reilly, right now. It's an fun and easy to read Design Patterns course, which is difficult to put down once you started it. The authors have a great sense of humour, and use a very practice-oriented approach. They tackle day-to-day problems by starting with the obvious solution an inexperienced programmer would use. Then they point out the problems with this solution, and step by step they work to the appropriate design pattern. Patterns are examined from different viewpoints, and the authors try to answer all the questions you might have.

I really recommend this book. In fact, I recommend the whole "Head First" series (I also own Head First EJB). These books are not usable as reference works, but they are wonderful for learning and mastering a subject.

The problem with patterns

[be-fan]

Patterns themselves are good to have in code, but the idea that they must be reimplemented for each case (as opposed to being packaged up into a concrete, first-class language object) really shows the limitations of mainstream languages. Peter Norvig (formerly at Harlequin, and now at Google) did a good writeup of the issue. Paul Graham also has an interesting take on this subject.