Re: Procedure types and dynamic binding

[scott@shuksan.UUCP (Scott Moody)]

> 
> >    I haven't done an extended investigation of the literature, but
> >    procedural variables in Algol-family languages would appear to
> >    be a research topic
>  <code not included> 
> 
> The final statement invokes the value of procvar, which is, of course,
> "inner".  The call of inner references the variable X declared in outer,
> which no longer exists.  This is the equivalent of the "dangling reference"
> problem when the address of a local variable is assigned to a global
> pointer.
> 

The C language solves this problem by not allowing 'inner' procedures at all.
Of course in C any address could be used and called, but it might not
point to anything meaningful.

I would thing the bigger problems with procedure parameters is in the 
parameters to those procedures; especially in Ada where there might be
overloaded procedures with very complex arguments. The syntax for 
specifying - and then checking at runtime that the user supplies
the arguments correctly can get very complex. 

I think Ada's  solution of requiring procedures to be supplied
to generics is a good compromise between allowing a users code to suddenly
jump to somewhere (hopefully not hitting any stars), and not having
them at all. I for one wouldn't mind procedure parameters and varaiables, 
ala C, but I can see that they go against the non goto rational behind Ada.

-- scott