Patternalia: December 2003 Archives

A number of us have put off following up on a fascinating, and
surprisingly productive OOPSLA Workshop from back in 2000, in
Minnesota.

Workshops -- Monday

Pattern Refactoring

I should dredge up my notes from this confab and post 'em...

5 September 2003
Friday
Death Valley Days #2

Recall that Ronald Reagan was one of the hosts of Death Valley Days…

An UP Observation: We are remoras on the Gang of Four barracuda. Only the GOF out-takes seem to have stuck:

EXTENSION OBJECT
EDITOR
TYPE OBJECT

NULL OBJECT
MVC/DOC VIEW

Three of these came from the Smalltalk world.

While there was some talk about the POSA patterns, they didn’t seem to make their way into the discussion all that much.

The test of a pattern is whether it really does

Do a GOF Talmud Page, to go with the GOF Thoughts shrine. Include Proxy Revisited, Null Object, Extension, Serializer, Type Object, Editor, etc.

The two observations above are from my 1997 notes. The following list is from the OOPSLA 2000 Workshop on Pattern Refactoring.

GoF Outtakes

1. Null Object
2. Abstract Class
3. Interface Class
4. Boilerplate Class
5. Type Object
6. Reifaction/Objectify
7. Serializer
8. Extension Object
9. Product-Trader
10. Bureaucracy
11. Role / Extension
12. Property
13. Whole Value
14. Abstract Object
15. Curried Object
16. Factory Object
17. Natural Object
18. Tools and Materials
19. Layer Object
20. MVC
21. Master-Slave
22. Publish-Observer
23. Presenter
24. Multiple Representations

Interpreter -
Abstract Factory -
Factory Method - -
Template Method - -
Decorator - - -

Iterator broadened to Streams

Services
Provides Information
Structures
Coordination
Controlss
Interfaces

Problematic

Proxy
Wrapper
Façade Adapter Decorator Bridge Proxy

Double Dispatch
Delegation
Abstract Class

There's been a thread in comp.object about refactoring to MVC. The intent is to tame a purported Swing UI monstrosity, and instead to move towards MVC by-the-Hoyle.

Hmm. I'd have scored Swing as being well within the broad outlines of MVCs intent penumbra, if not umbra, already.

The broader, more interesting question is why the Swing solution is regarded as a Frankenstein. Those components mesh better than most I've seen. Swing is a modern, third-generation (nth?) design / architecture. If programmers regard it as hopelessly Byzantine, what hope is there left? What's the problem with Swing? Is it so broad that its hard to learn? This could be so. My experience with it has been the learning curve is something well short of gentle. Issues like layout intrude far to early for my taste. Few components work out of the box. Is it capriciously arbitrary? Is it that the elements integrate in something short of a "seamless" fashion? They do seem to demand arbitrary trowel work, and more mortar, than one would expect of a framework that aspires to being the substrate for pre-fab solutions.

Is the problem that Swing had to be rolled out essentially finished? It had to emerge full-grown. Many species bear young that have to fend for themselves. Few that engage in the quality side of the quality vs. quantity trade-off abandon them. Yet, being bound to your mistakes as soon as you publish an API really really does constrain evolution. It's team players vs. defectors, as always, once again. How do we avoid the lumbering pageant of slow, coarse grained growth / expansion / dominance and extinction?

The picture to the right is of Tryve Reenskaug, who built the first implementation of MVC at Xerox PARC during the early '80s. (The picture was taken by yours truly at JAOO 2003, in Aarhus, Denmark last September.) Danny Dig, of UIUC's DCS, gave a nice presentation on the history of this pattern complex / compound pattern / architecture on the same day that Ralph Johnson braved the Big Ball of Mud quagmire. He accurately chronciled the trend towards closer coupling between Views and Controllers, and the ascendance of Mediator objects that buffer the relationships between Views and Domain objects.

The more intimate relationships between Views and Controllers has been driven in part by the absorption of input event generation facilities into the operating system, and its attendant low-level I/O facilities. The more refined divisions of labor among Views, Domain Objects, and the intervening Model / Adapter / Mediator / Mediaptors has been driven in part by the desire for GUI independence, and in part by the rise of automatic GUI code generation tools. Given this, designers are forced to foist their components on the world, ready or not. They must be treated as mature, full-grown artifacts before they are refined in the crucible of full-scale deployment.

Good judgement comes from experience Experience comes from bad judgement --The Murphy's Law Calendar (circa 1987)

This epigram is an old favorite of ours, and evidently quite a few others. I tried tracking it down, and came up with a gaggle of purported attributions, going back as far as Mark Twain. I'd like to believe the Twain attribution, but I've yet to find a solid citation for its source. The quip appears without attribution in a number of places, leading me to wonder if anyone really knows where it came from...

The remark has been variously attributed to:

Barry Le Patner
Jim Horning
Fred Brooks
General Bolivar Buckner
Rita Mae Brown
Will Rogers
Buster Bunny
Bob Packwood
Mickey Mouse
Texas Bix
Anonymous
Cousin Woodman
Mark Lacas
Arthur Jones
DC Stultz
Evan Hardin
Robert Kennedy
Lazarus Long
An Australian Aviation Magazine
Mark Twain

If you want people to always say "As Thomas Jay Peckish always says" before they say something, then Thomas Jay Peckish has to always say it...
--Thomas Jay Peckish II