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From: defaria@hpclapd.HP.COM (Andy DeFaria)
Newsgroups: comp.lang.ada
Subject: Re: How do I read in a character w/out pressing return ?
Message-ID: <920037@hpclapd.HP.COM>
Date: 21 Nov 90 19:25:12 GMT
References: <3858@uniol.UUCP>
Organization: Hewlett-Packard Calif. Language Lab
List-Id: <comp.lang.ada>

Seems we just went through this discussion a little while back.

There is no good way to do it using  pure Ada.  The  best way to accomplish
this, IMHO, is to interface with the OS system call that reads a character.
Encapsulate this  procedures (GET_KEY) into  a  package  (SYSTEM_CALLS)  to
minimize and localize portablity concerns.  The Ada call will 1) insure the
types coming  in  and going  out are  correct  and  pragma INTERFACE to the
correct system call (depending, of course, on the OS in question).

so (hypothetical example, assume reasonable type definitions):

package SYSTEM_CALLS is

   type STATUS_TYPE is new INTEGER;
   type CHAR_PTR    is access CHARACTER;

   OK : constant STATUS_TYPE := 0;

   function GET_KEY (THE_CHARACTER : in CHAR_PTR) return STATUS_TYPE;
   pragma INTERFACE (C, GET_KEY);
   pragma INTERFACE_NAME (GET_KEY, "getchar");
                     
end SYSTEM_CALLS;