Item2231: context-free vs classic registerTagHandler docco needs more info

Foswiki::registerTaghandler tells me nothing, and Foswiki::Func::registerTagHandler doesn't tell the plugin author why they would want to choose one over the other - just what it does.

I assume from the tone, that context-free is somehow better - is it, and if so, how is it better? is it faster, cleaner, sexier, or .... just different?

from the lack, and the fact only IF seems to use it, is it a justifiable extra code path (ok, so i may well think it is, but imo, it does deserve a little elaboration)

-- SvenDowideit - 10 Oct 2009

No, it's not justifiable.

Way back in prehistory, back when the dinosaur still roamed the earth, I tried to extend the tag syntax of macros such that they could be processed by a context-free parser (hence the "context-free") and bring them into line with HTML. This work was banjaxed by one particular tyrranosaur, who felt that the existing syntax was perfect. However by that time I had used it in a couple of places - most notable in the action tracker.

The syntax isn't vastly different from what's there; the differences are:

1. Use either type of quote for parameters
2. Optional quotes on parameter values e.g. recurse=on
3. Standardised use of \ for escapes
4. Boolean (valueless) options (i.e. recurse instead of recurse="on"

When I imported the macro parser in the Attrs class into the core, I kept the context-free syntax in the code, despite the fact that it had been blocked.

My inclination is to remove the doc from Foswiki::Func, perhaps with the above explanation in a comment on Foswiki::registerTaghandler.

-- CrawfordCurrie - 10 Oct 2009