Re: Processing of convenience variables for scripts ...

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Nov 21, 2002 at 04:22:53AM +1030, Richard Sharpe wrote:
> On Wed, 20 Nov 2002, Daniel Jacobowitz wrote:
> 
> > On Wed, Nov 20, 2002 at 11:32:24AM -0500, Andrew Cagney wrote:
> > > >The loop works, but add-symbol-file seems to be called without the 
> > > >>convenience variables being expanded.
> > > >>
> > > >>Have it got that right?
> > > >>
> > > >>If so, what would be the first step to get them expanded?
> > > >
> > > >
> > > >add-symbol-file takes constants, not expressions - so variables are not
> > > >expanded.  This should probably change but it's not clear how, given
> > > >the parser...
> > > 
> > > A quick/dirty hack would be:
> > > 
> > > 	eval .....
> > > 
> > > similar to the SH equivalent.  I suspect an eval will be needed anyway.
> > 
> > Honestly, I'd rather define the CLI grammar I've been talking about
> > than add any more quick hacks.  That's a good 6.0 thing to do, clean up
> > our CLI a little...
> 
> I have a short-term need and a long-term need. 
>  
> I am willing to expend effort on both. Where is the description of this 
> grammar?

In that case, in the short term, it would be worthwhile to implement
eval.  A simple version would just find any individual word that
started with a $ and substitute variables, and end up with something
like "eval add-symbol-file $name $addr".

The long-term grammar is still entirely in my imagination, alas.  It
requires:
  - Examining and recording the syntax of all our existing CLI commands
    (ouch!).  The manual is good but not complete enough IMVHO; people
    add quirks to functions without documenting them.

  - Determining which syntax structures we need to preserve and which
    should go.

  - Parsing CLI lines before calling the assigned functions, according
    to some data registered with the handler function.  This will
    involve changing syntax for at least some commands, I expect.  I
    think it's worthwhile but we need to see how invasive it would be.
    This can be done a bit at a time.

I want to get decode_line_1 tamed a bit first... David has made
astonishing progress cleaning it up, next will be to characterize its
behavior a little better.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer