All of the comments on and objections to the use of CIDTs of keyword-parameter values were interesting, and some of them were drôle.
The notion that coding say action=C instead of action=cancel is justified|justifiable if a comment explaining that C really means CANCEL is provided is, I think, self-defeating. If it is required, action=CANCEL should certainly be coded instead. I must again express a very different view. The notion that code should be self-documenting is and always has been chimerical. It should be lucid. Indeed, E. B. White's prescription for good [English-language] prose, that it should exhibit "lucidity, force, and ease", is equally applicable to statements in programming languages. Macro definitions should nevertheless be documented. It is my own practice to include a section called 'coding GUBBINS macro definitions' in a GUBBINS macro definition. This section explains the uses of it [chiefly] keyword parameters, the conventions available for coding them, the kinds of errors, often at boundary values, that can be made in coding them, and (where it is appropriate) a left-recursive BNF definition of the relevant syntax. As this practice suggests, it is my view that non-trivial macros and code in general are not at all self-documenting. Perspicuous names can make them easier to use than they would otherwise be, but clear documentation is always needed. Worse, attempts to dispense with such documentation are ill-advised. COBOL is the notorious example of an attempt to make a programming language self-documentating. The attempt failed abjectly, with pernicious side effects because prolixity was misidentified with clarity. Let me also say something about what Peter Relson calls "explicit abbreviations". I detest them as much as he likes them, and for two reasons. First, they are arbitrary and ad hoc; and ugly ad hoc, special-casing code is required to implement them. Second, they are too often culture-dependent. I can speak and write either British or American English unmixed. Most people cannot and do not need to do so, and they are thus unaware that these two very similar dialects have different abbreviation conventions. Worse, references that are obvious in one language community may be opaque or ambiguous in another. I still recall with pain a long discussion with an English-speaking Italian operator in Milano. The 'z EOD' for 'halt EOD' abbreviation puzzled him. It seemed entirely unmotivated, even though he was aware that 'z' was the last letter of the English (and indeed of the Italian) alphabet. The figurative use of 'z' to mean the end of something other than an alphabet nevertheless eluded him. This puzzled me, and I decided to conduct a small experiment. Knowing that he was a graduate of what Italians call a liceo classico and had thus studied ancient Greek I asked him if replacing 'z' by 'ω', omega, the last letter of the Greek alphabet, would hypothetically be more perspicuous for him; and his immediate answer was yes. He was familiar with the locution "from alpha to omega" as a description of "the complete range", "all possible values", and the like in three languages. It would be easy to multiply examples of this kind, but I have made my point even to those who disagree with it. Arbitrary abbreviations are often tone-deaf to culture and class differences. (Quite stupid upper-class Americans know what a regatta is; brilliant working-class ones usually do not.) Consensus is not likely to emerge from these discussions, but they were not time-wasting. John Gilmore, Ashland, MA 01721 - USA
