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To: Rob Quill <rob.quill@gmail.com>
Cc: gdb@sourceware.org
Subject: Re: Checking variable scope
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From: Jim Blandy <jimb@codesourcery.com>
Date: Wed, 29 Nov 2006 19:08:00 -0000
In-Reply-To: <20061129190614.GB9754@nevyn.them.org> (Daniel Jacobowitz's message of "Wed, 29 Nov 2006 14:06:14 -0500")
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Daniel Jacobowitz <drow@false.org> writes:
> On Wed, Nov 29, 2006 at 10:44:33AM -0800, Jim Blandy wrote:
>> I'm suggesting that you extend the grammar even further, by allowing
>> one to say things like this (assume there is no binding for 'a' in
>> scope, but there is a binding for 'b' in scope):
>> 
>> (gdb) print $in_scope(a)
>> $1 = 0
>> (gdb) print $in_scope(b)
>> $1 = 1
>> (gdb)
>
> Is extending the grammar really necessary?  That will already parse;
> it's the same as you'd use for a convenience variable named in_scope
> holding a function pointer.

I think so, because you need to prevent the reference to 'a' from
producing an error when you parse the expression.