[m-dev.] diff: use pretty printer in mdb

[Mark Anthony BROWN]

Mark Anthony BROWN writes:
> Ralph Becket writes:
> > > -----Original Message-----
> > > From: Mark Anthony BROWN [mailto:dougl at cs.mu.OZ.AU]
> > > Sent: 22 May 2000 07:46
> > >
> > > [...]
> > > +% Print using the pretty printer from the standard library.
> > > +% XXX the size of the term is not limited---the pretty printer
> > > +% provides no way of doing this.
> > 
> > In what sense are you using `size' here?
> 
> The number of functors in the term.  If there is a large branching
> factor in the displayed term, and the depth limit is not low enough,
> then a ridiculously large term might still be displayed.  The browser
> avoided this by keeping track of the number of functors, and displaying
> an ellipsis when the maximum size was reached.
> 
> This measure is still used by other parts of the browser (which did
> not appear in the diff).
> 
> >  The existing code (which
> > will go horribly wrong on very large terms [performance bug - a 
> > fix is in the pipeline]) allows you to specify the depth to which
> > pretty printing will go - as you've made provision for - and it
> > allows you to specify the notional display width (which it will
> > overrun if that cannot be avoided).
> > 
> > Do you mean that you'd like pprint to have a facility to clip
> > output to a given n x m character cell window?  If so, something
> > like that could probably be arranged.
> > 
> 
> That would be great.  Anything that puts reasonable limits on the
> number of lines displayed would be fine.
> 
> As for the performance problem, I think it can be solved by threading
> the available width through flatten, which should fail if there is not
> enough room for the flattened document.  This will allow the 
> condition (in be/3) to fail before the recursive call.
> 
> If this sounds like the right way to go, I'll test out the idea and
> post a diff soon.  Comments, anyone?
> 
> Cheers,
> Mark.
> 
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-- 
Mark Brown, PhD student            )O+  |  "Another of Fortran's breakthroughs
(m.brown at cs.mu.oz.au)                   |  was the GOTO statement, which was...
Dept. of Computer Science and Software  |  uniquely simple and understandable"
Engineering, University of Melbourne    |              -- IEEE, 1994
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