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From: edwards@rutabaga.cis.ohio-state.edu (stephen edwards)
Newsgroups: comp.lang.ada
Subject: Re: integer'image
Message-ID: <87789@tut.cis.ohio-state.edu>
Date: 29 Jan 91 19:55:37 GMT
References: <2390@shodha.enet.dec.com> <2638@sparko.gwu.edu> <557.27a476f2@vger.nsu.edu>
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Reply-To: stephen edwards <edwards@cis.ohio-state.edu>
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In article <557.27a476f2@vger.nsu.edu> g_harrison@vger.nsu.edu ((George C. Harrison) Norfolk State University) writes:
[ ... stuff about INTEGER'IMAGE deleted ... ]
>
>The problem really is the formatting of enumerated elements, integers, and
>[ideally] floats in the middle of string expressions.
>
>I am tired of writing
>
>PUT("The temperature at the");
>MYINTEGER_IO.PUT(N,5);
>PUT(" hour is");
>MYFLOAT_IO.PUT(TEMPERATURE,7,2);
>PUT(" ");
>MYTEMPERATURE_TYPE_IO.PUT(FAHRENHEIT);
>NEW_LINE;
>

Well, believe it or not, there are very trivial ways to do this easily.
Imagine being able to write the following magical expression:

    Put_Line("The temperature at the " & N & " hour is " &
    	     TEMPERATURE & " " & FAHRENHEIT);

Well, you can do this easily in Ada, albeit with the addition of a few
function definitions over and above those provided in Text_IO.  Of course,
you can wrap those in packages (generic ones, even) to use them over and
over--so you'll never have to write horrible, complicated output expressions
again! :-) :-) :-)

Of course, those who hate overloading or _use_ clauses, especially if they
are used together, will jump all over you.  However, it seems the code
is much more readable in the above example (not to mention easier to write,
and easier to maintain).  There _are_ times when these capabilities can
be very useful.

Also notice that none of these facilities require any changes to the
current Text_IO spec or implementation.  All can be layered right on
top of the existing package in a completely portable manner.

Note: actual definitions for the various instances of "&" in the above
example are left as an exercise for the reader.  For extra credit, think
about how one would extend such definitions to support the extra formatting
a fully general system might support (e.g., MyInteger_IO.Put(n,5); ...
MyFloat_IO.Put(temperature, 7, 2); ... etc., in the current Text_IO).



			-- Steve

Stephen Edwards					U.S. mail: 372 Jones Tower
e-mail    : edwards@cis.ohio-state.edu	           	   101 Curl Drive
home phone: (614)-293-0842			 	   Columbus, OH  43210