Re: Aliasing or referencing assignment

[David Trudgett <wpower@zeta.org.au.nospamplease>]

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

> "David Trudgett" <wpower@zeta.org.au.nospamplease> wrote in message 
> news:m3slwf3xcy.fsf@rr.trudgett...
>>
>> I'm having a little difficulty with assign by reference and assign by
>> value (copy) semantics in a piece of code I'm working on. In the
>> chunk of code that follows below, I want to avoid repeating
>> "Self.List(Opponent_Win, Can_I_Play)" many times, and just replace it
>> with a variable name like "C".
>>
>> "Self.List(Opponent_Win, Can_I_Play)" returns a Charles container
>> library Vector of Unbounded_String. The assignment:
>>
>>      C := Self.List(Opponent_Win, Can_I_Play); -- "List" is 2D array
>>
>
> How about something like:
>
>   declare
>       C : ListElementType renames Self.List(Opponent_Win, Can_I_Play);
>   begin
>         ... code that uses C ...
>        Append( C, To_Unbounded_String( "Blah blah" ) );
>   end;

That's exactly what I needed, Steve! Thanks. I actually tried to use
"renames", but I guess I must have got it slightly wrong.

It's very handy to be able to declare variables of restricted scope
like that in Ada, too! Like in Lisp (with LET and LET*), and unlike
Pascal.

Anyway, for the record, this is what worked:

      declare
         C : String_List.Container_Type
           renames Self.List(Game_Start, Nightmare);
      begin

         Append
           (C, To_Unbounded_String
            ("Go ahead, make my day..."));

         ... and so on

      end;



Cheers,

David

-- 

David Trudgett
http://www.zeta.org.au/~wpower/

"The high office of the President has been used to foment a plot to
destroy the American's freedom and before I leave office, I must
inform the Citizen of his plight." 

    -- John F. Kennedy, speaking at Columbia University, 
       10 days before his assassination