Re: Leading zeros with Int_IO.Put()? Or another package?

[Ken Garlington <garlingtonke@lmtas.lmco.com>]

Verne Arase wrote:
> 
> In article <3295F2A9.1EF0@lmtas.lmco.com>,
> Ken Garlington <garlingtonke@lmtas.lmco.com> wrote:
> 
>  >  use Ada.Text_IO.Editing;
>  >  ...
>  >  package Edited_IO is new Decimal_Output (type);
>  >  ...
>  >  Edited_IO.Put (n, To_Picture ("-99999999"));
>  >
>  >Interesting. They look reasonably similar to me. If anything,
>  >the Ada version makes it clear from the text that this
>  >I/O is using the Picture feature of the language. However,
>  >if you believe "P" is more readable in this regard, I
>  >suppose we'll have to agree to disagree...
> 
> Well, we are talking about a langugage primative rather than a subroutine
> library.

I'm not sure what a "language primitive" is, but any Ada compiler that implements
the Information Systems annex of the Ada standard (ISO/IEC 8652:1995) will support
the three lines written above (which can also be re-written as two slightly longer
lines, if desired). Specifically, the generic package
Ada.Text_IO.Editing.Decimal_Output is supplied by the compiler, just as the body of
SQRT would be provided (via a subroutine library, in many cases) by most FORTRAN
compilers.

The only definitions supplied by the user in this case, other than the lines
shown above, are "n" and "type", which refer to the value to be formatted and
its type, respectively.

Assuming that a generic package supplied by the compiler does not meet your
definition of a "language primitive," what's the relevance of this to the lines
you quoted? Is there a language design philosophy for PL/I that says "language 
primitives" should be very terse? Is this in the standard somewhere?

> Or are you saying that PayRoll is also built into the language (and
> implemented in a single statement)?

Since I don't know to what "PayRoll" you are referring, I certainly would
not claim it is part of the Ada language (or any other language :). I would
say something is "built into" the language if it is defined by the language
specification. For Ada.Text_IO.Editing.Decimal_Output, this is the case. See

  http://www.adahome.com/rm95/rm9x-F-03.html

"Edited Output for Decimal Types," in the on-line version of the Ada standard.

(By the way, is there an equivalent on-line version of the ISO PL/I standard?)

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