Re: [PATCH] -var-update

[Nick Roberts <nickrob@snap.net.nz>]

 > > >                                         BTW, why coerce_ref is not
 > > > suitable here?
 > > 
 > > coerce_ref ensures that the address is placed in the value's contents, not
 > > the actual value which is being referred to.
 > 
 > Did you try that?  That certainly shouldn't be true!

Yes.  Perhaps my summary isn't precise, but it didn't work.  My patch uses
value_at while coerce_ref uses value_at_lazy.  The comment says:

   Call value_at only if the data needs to be fetched immediately;
   if we can be 'lazy' and defer the fetch, perhaps indefinately, call
                                                    ^^^^^^^^^^^^
   value_at_lazy instead.  value_at_lazy simply records the address of
   the data and sets the lazy-evaluation-required flag.  The lazy flag
   is tested in the value_contents macro, which is used if and when
   the contents are actually required.

value_contents is not a macro (VALUE_CONTENTS used to be one) but a function,
and doesn't test the lazy flag.  So the comment is out of date, but perhaps
the `data' (I don't know what that means exactly) is never fetched when
-var-update is issued.

-- 
Nick                                           http://www.inet.net.nz/~nickrob