Re: Q: access to subprogram

[mab@dst17.wdl.loral.com (Mark A Biggar)]

In article <JSA.96Jul2221357@organon.com> jsa@organon.com (Jon S Anthony) writes:
>In article <Dtxu2p.97F@world.std.com> bobduff@world.std.com (Robert A Duff) writes:
>> During the design of Ada 9X, we proposed a SAFE way of taking 'Access of
>> more-deeply-nesting subprograms.  To this day, I remain astonished and
>> sad that this particular feature didn't make it into Ada 95.  After
>> all, even Pascal has that feature!  And GNU C, which allows nested
>> functions (unlike standard C) allows this feature.
>Is there an "elevator version" of why people didn't want this in?  Tucker,
>if you are reading this, what swayed you to not let this in????  It's
>not one of those things that bothers me all that much (well, it hasn't)
>but it is indeed curious...

If I remember right, it was felt that implementing "closures" (which is the
solution to this problem) placed an unacceptable distributed overhead
on programs that didn't use the feature.  Also I think that half the then
current Ada implementations were using "static links" and the other half
were using "displays" and implementing "clousers" would have been real
difficult for one of those groups (the "display" bunch I think).

--
Mark Biggar
mab@wdl.lmco.com