Re: Help!

[mfeldman@seas.gwu.edu (Michael Feldman)]

In article <9009241422.AA17160@wrdis01.af.mil> kmccook@WRDIS01.AF.MIL (Ken McCook;SCDQ;) writes:
>I'm working on a MIS project to be hosted on PC using MS-DOS
>and Ada. Have Alsys PC286 Ada Compiler.
>
>I'd prefer to write directly to the printer, but I could live
>with having to write to a file and then printing the file.

You probably can write to the printer. See below.
>
>I had hoped that Ada's Text_IO would have the capabilities 
>Turbo Pascal has for directing output directly to the printer 
>using Write and WriteLn? (And I'd hoped for direct keyboard
>reading as well like someone else on the net in recent days.
>Something like Turbo's "Read (kbd, X);".)

Text_IO does have "hooks" for doing this. Every CREATE or OPEN call
associates a file variable in your program with a string representing
the file's name as known to the operating system. I'm not all that
familiar with the Alsys system, but conjecture based on experience that
they provide a standard file name something like PRN or LPT1. Using
Meridian Ada, you'd write

    My_File_Name: Text_IO.File_Type;

    ......

    Text_IO.Create(File => My_File_Name, 
                   Mode => Text_IO.Out_File,
                   Name => "PRN");

and then all PUTs to My_File_Name would go to the printer. No, Ada does not
predefine the standard names, but probably it could not easily do so
because file naming conventions differ greatly from OS to OS (consider
DOS names with their 8-character limit vs. Unix names, etc. etc.).

So Ada does it JUST LIKE THE OTHER LANGUAGES, leaving it to the programmer
to do the mapping with a Create or Open call. Turbo Pascal is an exception,
not the rule, and can get away with it because Turbo Pascal exists (currently)
only for the DOS world. What is called Turbo Pascal for the Macintosh, for
example, is an entirely different Pascal-like language. And surely the
file names are different between DOS and MacOS.

The bottom line: most likely Alsys provides the standard DOS file names
for you to use. Try it.
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Prof. Michael Feldman
Department of Electrical Engineering and Computer Science
The George Washington University
Washington, DC 20052
202-994-5253
mfeldman@seas.gwu.edu
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