Re: [Q] Returning Strings From A Function

[dewar@merv.cs.nyu.edu (Robert Dewar)]

John McCabe said

<<would be a solution, but I felt sure there was another way to do it so
that I could declare File_Name as an object of a string type e.g.:

type File_Name_Type is new String (1..12);

then use:-

procedure ...

   File_Name : File_Name_Type;

begin
   :
   File_Name := Text_IO.Name (File);
   :
end...

or something similar. But unfortunately this is obviously not possible>>


John, it is still very difficult to understand what you are asking for.
Your code above makes perfect sense if you want File_Name to be 12 characters
long, and of course the assignment will check for 12 characters.

That is apparently NOT what you want, so it is not clear what "this" is
that is "obviously impossible". You need to say what you have in mind.

Do you want to pad the name with blanks to make the length 12? In that
case you could write

   File_name :=
     Ada.Strings.Fixed.Head (Text_IO.Name (File), File_Name'Length));

which seems pretty clear.

If you what you wanted was a string whose maximum length was 12, but to
which smaller strings could be assigned, then Ada.Strings.Bounded is just
the ticket.

It is simply not at all clear to me from the above code what you have in
mind. When you write some perfectly legal, perfectly sensible Ada code,
and say "What I wanted was to do that, but it is impossible, you are
obviously trying to say that you expected some other semantics from the
code than the semantics defined in Ada. That's fine, anyone is allowed
to say such things, and it is often interesting to know what features 
people want, but it is inmpossible to *guess* from this perfectly 
reasonable Ada code what you wanted it to do that was different from
what it actually does in Ada.

So why not try again saying exactly what you have in mind in a clear form.
Don
't try to write Ada, since apparently you think you can't do what you
want to in Ada. Instead describe informally what it is that you think
you cannot do that you would like to do.