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Re: scheme.el bug & fix
Re: scheme.el bug & fix
Mon, 17 Feb 2003 09:39:17 -0500
> It turns out the problem is that
> (with-syntax-table st (modify-syntex-entry foo bar))
> does not modify `st' because `with-syntax-table' does not use `st'
> but a copy of it. Actually it's even documented in the docstring.
> This sounds silly. Does anybody have an idea why it is defined that way ?
> If not, any objection the patch below which should also improve
> (very marginally) the performance of Emacs ?
> Are you sure that you are not going to break plenty of existing code
> this way?
I grepped through lisp/**/*.el and couldn't find a single case where
the table needed to be copied.
> People could very legitimately have relied on the present
> behavior, which is, as you state yourself, very explicitly mentioned
> in the doc string. The reason for the "silly" behavior seems obvious:
> to avoid accidental modification of st.
But it is extremely rare to use modify-syntax-entry with no
third argument and within a with-syntax-table thing, so the
risk of accidental modification is basically inexistent.
As a matter of fact, syntax-tables are very rarely modified at
all, other than when they're created.
> Is there any reason why scheme.el can not possibly define its syntax
> table in a more standard and more natural way?
Of course, it can. That's a separate question. Please someone install
the patch as soon as you can: it's obviously the right thing to do.
> (I believe it is meant to very temporarily change the syntax table of
> the current buffer, not to be used to actually define syntax tables.)
Indeed, and you don't want this temporary syntax-table-switch to make
a copy of the table and then drop it on the floor (turning it into
garbage) unless there's a very good reason for it.
For example with-category-table does not copy the table.
- scheme.el bug & fix, David PONCE, 2003/02/14
- Re: scheme.el bug & fix, Stefan Monnier, 2003/02/16
- Re: scheme.el bug & fix, Luc Teirlinck, 2003/02/16
- Re: scheme.el bug & fix,
Stefan Monnier <=
- Re: scheme.el bug & fix, Luc Teirlinck, 2003/02/17
- Re: scheme.el bug & fix, Stefan Monnier, 2003/02/18
- Re: scheme.el bug & fix, Richard Stallman, 2003/02/19
- Re: scheme.el bug & fix, Stefan Monnier, 2003/02/19
- Re: scheme.el bug & fix, Miles Bader, 2003/02/19
- Re: scheme.el bug & fix, Richard Stallman, 2003/02/20
- Re: scheme.el bug & fix, Stefan Monnier, 2003/02/20