Checking variable scope

["Rob Quill" <rob.quill@gmail.com>]

Hi,

I am trying to make it possible to be able to check if a variable is
in scope at a given time. My current implementation for this involves
adding a parameter to parse_expression, and the parsing functions it
calls, all the way until it gets to the line:

if (sym == 0)
    error ("No symbol \"%s\" in specified context.", copy_name ($3));

in c-exp.y

as which point it doesn't call error, but calls another function which
returns a value signifing that the variable is not in scope.

Whilst this is OK, in that it (should) work, I was wondering if anyone
had a neater way of implementing it?

Thanks for your time.

Rob