bug#25903: Question re syntax tables and unexpected behaviour in C/C++ major mode

[Alan Mackenzie]

Hello, Peter and Noam

On Wed, Mar 01, 2017 at 23:49:17 -0500, npostavs@users.sourceforge.net wrote:
> Peter Milliken <peter.milliken@gmail.com> writes:

> > My code works fine in buffers that have Python, Ada and Lisp major
> > modes but it experiences difficulties in buffers with C/C++ major
> > mode. Basically, when in a C/C++ buffer, the code locates text within
> > "<>" pairs as well as "{}"/"[]" pairs. I really don't want my code to
> > have an (ugly) exception case where it tests "if in C/C++ mode then
> > check if <> has been detected and skip over them and continue looking
> > for {}/[] pairs"

Depending on your exact usage, it might be well worth your while leaving
the stuff for strings and comments in your syntax table.

> You'll probably have to though.  In C++, "<" matches ">" when they
> denote template arguments.  cc-mode implements this by adding text
> properties to those characters so that they have pair syntax.  Changing
> the syntax table doesn't change the text properties, so for those
> characters, the syntax stays the same.

What can be done, though, is to disable the effect of the syntax-table
text property by binding parse-sexp-lookup-properties to nil.

> Use C-u C-x = to check the syntax and properties of a particular
> character.

-- 
Alan Mackenzie (Nuremberg, Germany).