Doing Design

In an extract from the new edition ("2.0", indeed) of Software Conflict Robert L. Glass revisits his prior discussion of "design" in software. He focuses on the undoubted fact that design is a cognitive process. It's perhaps a sad reflection on the state of the industry at the time he was writing that this should have been a noteworthy observation.

Where to begin? How to proceed?

Anyway, it seems that Glass undertook a commendable self-assessment of his stance on design, found it wanting and turned to the research of Bill Curtis and Elliot Soloway. As reported by Glass, after a series of "protocal studies" came up with roughly this description of what programmers do when they design:

1. Construct a mental model of a proposed solution to the problem
2. Mentally execute the model to see if it solves the problem
3. It doesn't, so see which parts of the problem the model fails on and enhance it
4. Repeat until good enough

Strangely, Glass calls this a "well defined process" and looks to the implications of this "new concept of design as a mental process."

By the way, Google wants "protocal" to be a typo for "protocol" but apparently it isn't. "Protocal" seems to mean "talking about what you're doing while you do it."

The problem with the design process as described above is that it has by itself nothing to say about where these mental models come from, or how they are compared or improved. Glass quotes Charles Simonyi on this, thus:

The first step in programming is imagining. Just making it crystal clear in my mind what is going to happen.

Which all, as a description of the design "process", seems only little more useful than the Feynman Problem Solving algorithm (*). Especially since one of Glass's goals in studying this matter was to find a better way to teach design.

Tools for the mind?

In the 2006 update to this essay Glass reports on the outcome of the Curtis/Soloway research: nothing. Apparently, they gave up. Glass states:

Because the nature of design, they discovered, is so intensely cognitive, happening inside the mind at mind speed, the researchers could conceive of no useful tools to help in that process!

What!? No useful tools to help with a process "inside the mind". Come now! I'm not sure I believe that this is what two smart guys like that concluded, unless by tool they meant some clanking monstrosity that would, you know, run on a computer.

Well, programmers aren't the only people who do design, nor who introspect upon their own design activity. In 1964 (about 20 years before the research Glass is talking about) Christopher Alexander produced his doctoral thesis, Notes on the Synthesis of Form, which describes how the "imagining" takes place within a culture and a tradition (the design patterns movement inspired by Alexander seeks to make these things explicit for the society of software builders, and others) in both self-conscious and un-selfconcious modes, but more importantly explains how to traverse the loop from less good to more so. Laurent Bossavit gives a good overview of these ideas. Alexander even went so far as to write some computer programs to help architects and planners use these ideas. That would be a "tool". Oh dear.

As Prof. Sir Tony Hoare has put it

If only we could learn the right lessons from the successes of the past, we would not need to learn from our failures.

(*) The Feynman Problem Solving Algorithm

1. Write down the problem
2. Think very hard
3. Write down the solution