Steve Yegge: Singleton Considered Stupid

http://steve.yegge.googlepages.com/singleton-considered-stupid

by nickb • 18 years ago

33 37 18 years ago

steve.yegge.googlepages.com

Tichy5• 18 years ago

Ironically, my experience was that everybody seemed to only understand the factory pattern. Wherever I worked, people loved using factory, whether it made sense or not.

sah2• 18 years ago

I can't stand it when people use Factory in Python. In Python, classes are objects -- you can just pass a class into a function as a parameter!

globalrev• 18 years ago

you cant in java!?

marcus• 18 years ago

I once saw code that had factories that generated factories that generated factories. Yuck...

Like the ancient world view, "it's turtles all the way down"

Tichy5• 18 years ago

But think about the generalizations it affords... ;-)

nuggien• 18 years ago

There are no stupid design patterns, only stupid programmers who don't understand why they are using the design patterns.

jauco• 18 years ago

only stupid programmers

the thing is, you can't just read a book about design patterns (any book, no matter how well written) and know when to apply them. You'll have to try it, make mistakes, learn from them, make mistakes in the opposite direction and so forth.

People should build some personal throwaway projects and cram in every design pattern they know. That should at least get them started on the learn/mistake cycle. At least it did so for me. Though in my last project I was totally abusing the factory pattern while all the while chanting "I shall not use patterns when they are not necessary" :blush:

andrewl• 18 years ago

That's right. The programmer may not be stupid at all. He or she may just be in the middle of learning patterns.

One might say that only stupid speakers make simple grammatical errors. Or they might be beginners in a second language. I hope and expect to always be a beginner in something in my life, whether it's a new computer or human language, a new craft, or some other new way of thinking.

By the way, Peter Norvig says that in Dylan or Lisp, 16 of 23 patterns are either invisible or simpler.

That's from the "Design Patterns in Dylan or Lisp" slide from his Design Patterns presentation at:

http://www.norvig.com/design-patterns/

ComputerGuru3• 18 years ago

OK, so reading this article is enough to thoroughly convince one to rethink the usage of Singletons. But what other design patterns would you guys recommend? Most of the common design patterns are some form of Singleton implementation or the other and suffer many of the same drawbacks Steve points out in the article - what are the alternatives?

(I've been making do with custom interactor classes that perform object sharing by using linked-list of class instances with a custom "mapper" and though it works great it's really hard to explain to anyone).

Also - any books you guys would recommend as an alternative to Design Patterns?

DanielBMarkham3• 18 years ago

I never liked the patterns books because I always thought they gave you solutions without knowing what the problem was.

Ever learn MVC? Might be a good place to start.

ComputerGuru3• 18 years ago

When you write your own MVC you'll come right back to the original patterns question. MVC is just the thing programmers interact with so they don't have to deal with inter-class interactions directly. But the MVC framework itself needs to manage those interactions somehow, using one pattern or the other.

mojuba• 18 years ago

Curiously, somehow only in OOP there is a real need for teaching/learning "patterns", whereas outside of the everything-is-object world anything you do is a "pattern".

hobbs2• 18 years ago

Indeed, I found that this statement sounded alarms in my critical thinking cortex:

"the Singleton "pattern" encourages you to forget everything you know about OO design, since OO is hard, and procedural is easy."

Why, oh why, are we encouraging people to use OO 100% of the time, when it's admittedly harder than the alternatives? (I'm looking at you, Java.) Methinks the bandwagon continues to play on, even after two decades...

pistoriusp• 18 years ago

Something that Alex Martelli said in one of his talks when I was starting off with Python was something along the lines of: "Ignore OOP!"

I had never heard anyone suggest anything like that before, I think some developers think OOP is "the way forward." I spent many months trying to force my mind to think in an OOP manner, now I don't even bother. Occasionally I find a place where it does work, but it's definitely not a magical bullet.

bvttf• 18 years ago

Pages 243 to 256 are, in my copy at least, the Interpreter pattern, in case anyone else was wondering.

icky2• 18 years ago

I wasn't, but my Observer was...

andreyf• 18 years ago

Pages 243 to 256 are, in my copy at least, the Interpreter pattern

http://en.wikipedia.org/wiki/Interpreter_pattern

From what I can tell, using this is a pretty clear sign you should be using a language with macros...

Hexstream• 18 years ago

"In my Data Structures course in college, when we got to AVL trees, my prof turned and wrote on the board, in huge, clear letters:

AVL Trees are EVIL

...and that's all we had to learn about them. He had us implement red/black trees and splay trees instead. To this day, I have no idea how threaded AVL trees work. But if that's OK with Dan Weld, it's OK with me. "

Thank goodness it wasn't: "LISP is EVIL". Or replace lisp by anything useful and generally misunderstood.

ambition• 18 years ago

I think the professor's point is that using red-black trees is a dominant strategy over using AVL trees.

alex_c• 18 years ago

Do I get bonus points for not really seeing much point to the Singleton pattern when I read the GoF book? In fact, I can generalize that to say that all the patterns seemed either obvious or pointless.

I still haven't decided what that means about me as a programmer.

icky2• 18 years ago

> Do I get bonus points for not really seeing much point to the Singleton pattern when I read the GoF book?

This comment entitles the bearer to one (1) Hacker News Bonus Point.

Don't spend it all in once place.

shiro• 18 years ago

My reaction was similar. Later I found they were useful as a communication medium when you worked in a team that were doomed to use Java or C++; walking may be a natural thing for you that wouldn't need an explanation, but knowing that action is called "walking" helps when you explain to someone how you get to somewhere.

Of course, if you're using more succinct programming languages, it may be much faster and accurate to write a line or two of the actual code to show what you mean, rather than remembering all those names of the patterns.

DanHulton2• 18 years ago

When writing a game, I tend to have a singleton "Game" or "World" class (well, actually a static class, I don't bother with all the getInstance() crap), and from there a bunch of proper classes all "owned" by Game. Now, I'm basically using static classes as a namespace here, but is this really that harmful? If so, what options do I have?

Tichy5• 18 years ago

I guess it will fly in your face once you'll try to create multiplayer games and serve several games at the same time?

What do you gain from making a game a singleton?

DanHulton2• 18 years ago

Well in that case, I'd have a Server class and a Client class. One handles logic and the other handles display and input.

And actually, for my last little prototype (now that I think about it), I didn't make it a singleton, I just had a single public instance of it.

Question retracted.

ken• 18 years ago

"The problem is, about 1/3 to 1/2 of them were basically cover-ups for deficiencies in C++ that don't exist in other languages. Although I'm not a huge Perl fan anymore, I have to admit the Perl community caught on to this first (or at least funniest). They pointed out that many of these so-called patterns were actually an implementation of Functional Programming in C++."

Compare Norvig (1998): "Design Patterns in Dylan or Lisp: 16 of 23 patterns are either invisible or simpler". http://norvig.com/design-patterns/

Steve Yegge: Singleton Considered Stupid

Related Stories