Re: loop and block question

[bobduff@world.std.com (Robert A Duff)]

In article <2svi8g5rzr.fsf@hp755d2.eurocontrol.fr>,
Steve Jones - JON  <jon@hp755d2.eurocontrol.fr> wrote:
>You have reused Some_Loop_Name these labels should be unique just like the
>compiler output tells you. Having never used the dreaded GOTO I cannot
>be certain but I think that this is what the Labels COULD be used for
>(if you wanted to die a slow and painful death).

No.  Goto labels have a different syntax from loop names (and that's
good).  But they both have to follow the same unique-within-procedure
rule.

>Now a question, why does Ada have GOTOs,

Hey, are you trying to start a war?  ;-)

>... why does code need to be changed
>to avoid GOTOs problems ?

Good question.  I'm not entirely sure why loop and block names have to
obey the same rules as goto labels.

>... I remember having a bunch of exception handling
>blocks within a case statement, I had to create individual names for
>each one rather than just using a unified label (eg Exception_Block)
>we can overload everything BUT labels.

No.  At a given place in your code, you cannot overload two names,
unless *both* are subprograms.  This is a design principle of Ada 83,
for better or worse.  And to get around, the language definition
pretends that enumeration literals are "really" functions.  And to get
around it in a different way, integer literals are of some magical type
called universal_integer, and implicit conversions happen.

>GOTO has unusual syntax so why not specific GOTO Labels ?

The syntax of goto labels is different.  But goto labels occupy the same
namespace as everything else.  You can't have a variable called X and a
label called X in the same scope.  Are you saying that should be
allowed, and that overload resolution should distinguish "X := 1" and
"goto X;"?  IMHO, making the overload resolution rules too smart is not
a good idea.

- Bob