Re: A vision for multiple major modes: some design notes

[Alan Mackenzie <acm@muc.de>]

Hello, Richard.

On Sat, Apr 23, 2016 at 08:38:04AM -0400, Richard Stallman wrote:
> [[[ To any NSA and FBI agents reading my email: please consider    ]]]
> [[[ whether defending the US Constitution against all enemies,     ]]]
> [[[ foreign or domestic, requires you to follow Snowden's example. ]]]

> Are you saying that there won't be a character with the "open island"
> in the syntax table, but rather a text property will give a particular
> string in the buffer the "open island" syntax?

Yes.  I think it would most unwise to assign a character such a syntax
in the syntax table - the island boundaries would be unstable, existing
or not existing depending on the syntax table of the island one was
currently in.  I anticipate writing a warning about this in the Emacs
Lisp manual.

> That makes more sense.  But I think that in some cases "separate
> islands" might be a better designation.  For instance, consider the
> three sections of a Bison input file.  They are separated by a
> delimiter.  It would be artificial and arbitrary to try to divide up
> the delimiter into a string to end the previous island and a string to
> start the next one.

I think Bison and Lex are somewhat special cases; they each divide a
file into three sections of equal status, rather than there being a
containing mode and sections contained within it.

> Which reminds me that the first island in the Bison input file
> has no string to "open" it.  It starts at the start of the buffer.
> And the third island ends and the end of the buffer.

A workaround for this would be to have the first section being the
"super mode" and containing the second and third sections.  The
delimiter "%%" between sections 2 and 3 has space to hold both an island
close and an island open, despite what you say about this being
artificial, etc.  I don't see there would be an absolute need for there
to be a "close island" mark at the end of the buffer.

> -- 
> Dr Richard Stallman
> President, Free Software Foundation (gnu.org, fsf.org)
> Internet Hall-of-Famer (internethalloffame.org)
> Skype: No way! See stallman.org/skype.html.

-- 
Alan Mackenzie (Nuremberg, Germany).