Re: Syntax-table text properties
I've now noticed your message regarding the syntax-table text
properties.
I believe adding this feature to XEmacs would be very worthwhile, and a
correct patch that implements this would certainly be accepted by the
maintainers. I myself considered adding this, but never got around to
it, partly due to my not being familiar with Emacs syntax engine. As a
former Perl hacker, I've often been extremely annoyed at XEmacs'
inability to comprehend the finer points of Perl syntax.
Note however that, under the hood, XEmacs is quite different from GNU
Emacs. Specifically, there are no "text properties" in XEmacs, but
"extents". You would need to implement a `syntax-table' extent
property and make the code in syntax.c respect it. You might want to
introduce some optimizations to make this efficient (repeated querying
for extents from within syntax.c could be slow), but it's probably to
early to talk about that.
As XEmacs text-property implementation is in fact based on extents,
everything you implement for extents would automatically reflect the
text properties, so you don't need to worry about modifying Perl mode
at this point.
You would also need to consider what happens when two overlapping
extents both have syntax-table properties define. You might want to
consider implementing a cascading scheme, so that e.g. the inner extent
takes precedence over the outer one, or you might declare such
overlappings undefined, if you think it's an overkill.
Also note that syntax engine implementation in XEmacs is probably
different from the GNU Emacs one. You might want to sync it with the
latest one in GNU Emacs, while being careful not to break XEmacs in the
process. Syncing is often tricky.
All in all, I don't want to give an impression that I'm trying to
discourage you. In most places, XEmacs is very well written, and
adding new features is more of a challenge than just boring typing. I
hope that you will decide to undertake implementing this feature. You
have my support.
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