Subject: Re: Proposal: (node ...) construction rule type From: David Megginson <ak117@xxxxxxxxxxxxxxxxxxx> Date: Thu, 14 Aug 1997 13:30:13 -0400 |
Paul Prescod writes: > I'll leave that as an excercise for the reader. You are right that it is > certainly in the "Scheme" (and DSSSL) tradition to describe language > constructs in terms of more primitive constructs. It's more than just a tradition -- it's an important (and required) sanity check that accomplishes at least two goals: 1. Make certain that the language is logically and completely described and implemented. 2. Avoid creeping featurism. Your proposal is useful because it provides a fundamental mechanism for describing the higher-level construction, rather than simply adding another higher-level construction to the list. > > The problem is that there is no mechanism in DSSSL for adding > > construction rules, the way that there is for adding flow-object > > classes and external procedures. If James modifies Jade to include > > the 'node' construction rule, I suspect that his program will no > > longer be DSSSL-compliant (at least, until the standard changes). > > Then again, he could provide a command-line option to disable the > > extension for full DSSSL compliance. > > James has other DSSSL extensions. As long as he can accept a standard > stylesheet Jade would be DSSSL compliant. Yes, but all of Jame's other extensions can be declared in DSSSL-compliant ways, using 'external-procedure', 'declare-characteristic', or 'declare-flow-object'. There is no corresponding 'declare-construction-rule' procedure in DSSSL. I don't know how much of a problem that might be for James. > Anyhow, I think that all of the likely DSSSL implementors are on this > list. If there is a big flaw in the proposal then they will probably say > so. If not, they can implement it. As you point out, it doesn't seem > difficult. With Jade, at least, it's almost trivial -- SP is already providing all of the required information (although optimising the character handling would take a bit of work). From what I've seen, anything based on NXP should have no problem either. All the best, David -- David Megginson ak117@xxxxxxxxxxxxxxxxxxx Microstar Software Ltd. dmeggins@xxxxxxxxxxxxx http://home.sprynet.com/sprynet/dmeggins/ DSSSList info and archive: http://www.mulberrytech.com/dsssl/dssslist
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