Exclamation mark in a syntax table

Exclamation mark in a syntax table

[Óscar Fuentes]

On a mode for an internal programming language that considers a leading
`!' as *not* part of the symbol, I put this:

      (modify-syntax-entry ?! "'   " table)

but symbol-at-point for !foo still returns !foo. Furthermore, I see no
way of specifying that a leading ! is an expression prefix but in any
other place it is a symbol constituent.

Re: Exclamation mark in a syntax table

[Stefan Monnier]

> but symbol-at-point for !foo still returns !foo. Furthermore, I see no
> way of specifying that a leading ! is an expression prefix but in any
> other place it is a symbol constituent.

You can try a syntax like "_ p".  But it all depends on the details of
what you really want/need.  There's a good chance you'll need to use
syntax-propertize-function to give different syntaxes to those
different cases.


        Stefan

Re: Exclamation mark in a syntax table

[Óscar Fuentes]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> but symbol-at-point for !foo still returns !foo. Furthermore, I see no
>> way of specifying that a leading ! is an expression prefix but in any
>> other place it is a symbol constituent.
>
> You can try a syntax like "_ p".  But it all depends on the details of
> what you really want/need.  There's a good chance you'll need to use
> syntax-propertize-function to give different syntaxes to those
> different cases.

syntax-propertize-function looks scary.

As for

(modify-syntax-entry ?! "'   " table)

it works as expected after reverting the buffer. IIRC when I inserted

(modify-syntax-entry ?\? "_   " table)

into the mode's syntax table it didn't require a buffer revert.

Thanks.