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

[rav@goanna.cs.rmit.edu.au (robin)]

ok@goanna.cs.rmit.edu.au (Richard A. O'Keefe) writes:

	>rav@goanna.cs.rmit.edu.au (robin) writes:

	>>Ken Garlington <garlingtonke@lmtas.lmco.com> writes:
	>>	>From the Introduction section of ISO/IEC 8652:1995:

	>>	>"The need for languages that promote reliability and simplify maintenance
	>>	>is well established. Hence emphasis was placed on program readability over
	>>	>ease of writing."

	>>Ada clearly failed in this aspect.

	>This is not clear at all.

---It is abundantly clear that it failed as to ease of writing.
Various postings suggested that the conversion could be done in up to
82 lines of Ada code, whereas PL/I requires one simple line.

	>I have used a great many programming languages,

Haven't we all!

	>and find Ada to be _dramatically_ more readable (in terms of
	>how well I can read other people's code) than most of them.
	>It beats C and C++ by a country mile,

On this we agree.

	>and I find that it beats PL/I as well.

On this we don't.

	>One of the reasons is that conversions are explicit.

	>>No excuse for having everyone who wants to use such a facility
	>>to have to write it.

	>*BUT THEY DON'T*.

But they do, and there were various postings all giving different
ways to accomplish it in Ada.

	>It is a common rhetorical device of yours, rav, to take a
	>true statement "someone must write X", and use the _false_
	>statement "everyone must write X" as a stick to beat Ada with.

	>>It is, after all, avalable in a number of languages including COBOL
	>>and PL/I.

	>We are specifically talking about converting numbers to text.
	>If you want a list of languages with such features,
	>add Burroughs Extended Algol, and Algol 68.

Those (COBOL and PL/I) were only examples.  Even BASIC has it.

	>Also add Ada 95.

Only if it's implemented.

	>We have GNAT, and the current GNAT documentation says all
	>the annexes are supported.
	>I _have_ tried picture editing in GNAT; it works fine, and it
	>is no harder and no easier to write Ada pictures than COBOL
	>or PL/I pictures.

Only where Ada supports a CoBOL or PL/I equivalent, as you
admit below.

	>>The simplicity and usefulness of PL/I in producing
	>>zero suppression/insertion of characters/general editing/
	>>in a variety of forms (integer, fixed-point, floating-point) and suitable
	>>for business and science cannot be refuted.

	>Can I refute the usefulness of PL/I for this?
	>I cannot, and would not want to.
	>Can I refute the simplicity of PL/I for this?
	>Well, it depends on what you you mean.
	>As noted above, I don't find it any harder to write
	>Ada pictures than PL/I pictures, and I welcome the
	>level of detail in the ADA 95 LRM.
	>I've used pictures in Burroughs Algol, COBOL, and PL/I, and
	>the devil is in the details.
	>Concerning the actual _use_ of pictures, if you use named
	>pictures in PL/I, there is very little to chose.

There is considerable difference -- in favor of PL/I -- between the
two.  After all, you have demonstrated it!

	>If you
	>_don't_ use named pictures (by which I mean ones declared
	>in a PL/I DECLARE statement or an Ada object declaration)
	>then using "magic strings" is just as bad as using "magic
	>numbers".

???????
Now why would you bury a picture specification in a remote place from 
the output statement that uses it?

	>>As I indicated earlier, just one short line will suffice! :

	>>put edit (d) (P'999.V999');

	>I note that Ada 95 pictures offer some features missing from COBOL-85
	>and that they're pretty useful.

	>I note that Ada 95 makes it pretty easy to read a picture from a file,
	>or compute on on the fly by some other method.

A facility that's available in IBM's PL/I for OS/2, Windows 95/NT and
AIX.

	>In particular, from
	>the attributes of "d" in an example like this.)

	>I willingly concede that it is a nuisance that Ada 95 pictures apply to
	>decimal fixed point numbers, not integers or floating point numbers.
	>(In particular, Ada 95 pictures have no "exponent picture" support.)
	>I also willingly concede that waiting until run time to check pictures
	>whose strings are known at compile time is not what I would have chosen.

	>In the case of writing out integers with pictures,
	>I don't greatly mind having

	>	type Decimal_Integer is delta 1.0 digits 9;
	>	package Decimal_Integer_Editing is new
	>	   Ada.Text_IO.Editing.Decimal_Output(Decimal_Integer);
	>	use Decimal_Integer_Editing;

	>ONCE somewhere in a program (probably written by someone else) and
	>then doing
	>	Put(Decimal_Integer(X), To_Picture("-999_999_999"));
	>or whatever.  

Thank you for proving the point!  PL/I's

   put edit (d) (P'-999,999,999');

is a lot simpler. What's more, you don't have to hunting for
Decimal_Integer to find out what it does.

P.S. Check out PL/I's drifting user-specifiable currency symbols etc
for picture editing.  Great fun!

	>Richard A. O'Keefe; http://www.cs.rmit.edu.au/%7Eok; RMIT Comp.Sci.