Re: Reprise: 'in out' parameters for functions

[Stephen Leake <stephen_leake@acm.org>]

"Alexander E. Kopilovich" <aek@VB1162.spb.edu> writes:

> Stephen Leake wrote:
> 
> > This is what I wanted to declare:
> >
> > function Parse
> >   (Error_Label : in     String;
> >    Token       : in out Token_List.List_Iterator)
> >   return String;
> >   --  Process Token, which should contain '([Config_File =>] <string>)'.
> >   --  Return the string.
> >   --  Delete parsed tokens from Token.
> >
> One thing is missing in this your explanation: why exactly you don't want to
> make that List_Iterator global (instead of passing it as IN OUT argument) ?

Hmm. I suppose that is a legitimate question. 

My answer is "I never make anything global unless it has to be,
because that usually leads to trouble".

In this case, Token is actually the contents of an aggregate, part of
a larger statement that is dynamically allocated. It must be modified
in place; copying it to a global to pass it to this routine would be a
maintenance nightmare.

And no, I don't consider "Ada doesn't allow 'in out' in functions" a
good reason to make something global; I'll change it to a procedure
first.

-- 
-- Stephe