Re: Variable list parameters

[Robert A Duff <bobduff@shell01.TheWorld.com>]

"Steve" <nospam_steved94@comcast.net> writes:

> <shaunpatterson@gmail.com> wrote in message 
> news:9e4ce016-d6ab-49de-b6f7-e46c59e047b1@t47g2000hsc.googlegroups.com...
>> Does Ada have variable length parameter lists?
>>
>> i.e  void printf (char *, ...)
>
> No.
>
> You can achieve similar results by making a variable length array and 
> passing the array as an parameter:
>
>    type arg_array is array( Positive range <> ) of integer;
>
>    procedure process_args( args : arg_array ) is
>    begin
>      null;
>    end process_args;
>
> ...
>
>    process_args( ( 1, 2, 3 ) );

That works fine for integers, but if you want to pass Strings
(a common case), it gets rather ugly!

> If you need to have different argument types you can either make the 
> elements of the array tagged or variant types.

An array of variant records works, so long as the discriminant has a
default value.  As for array of tagged, well, it has to be class-wide,
and array-of-class-wide is illegal, so it has to be
array-of-pointer-to-class-wide.

- Bob