Re: Using Get_Immediate to read keystrokes.

[dale@cs.rmit.edu.au (Dale Stanbrough)]

Marin David Condic wrote:

     So I got a request from a user to improve the behavior of a little
     command line oriented application. Currently the application uses
     Ada.Text_IO.Get_Line to read in commands. The user wants to use
     the up-arrow key to recover previous commands.
 
     I'm thinking "No Problem" I've got a standard call in Text_IO
     called Get_Immediate - all I have to do is create a command buffer
     & do my own line editing & I can give him the desired feature and
     move on with my life.
 
     Well, using GNAT v3.09 on a Sun - SunOS 5.5.1, the behavior of
     Get_Immediate - while not irrational - is at least not exactly
     everything I want. I wrote a little quickie test program (below)
     which lets you see what the Get_Immediate sees for any given
     keystroke. My problem is that if I want to write my own little
     line editor to include a buffer of previous commands, you really
     don't want every keystroke echoed to the screen. Unfortunately,
    that's what happens - including escape sequences for the arrow
     keys, etc.
 
     Does anybody know of a trick on the Sun or using the GNAT compiler
     which will shut off character echoing so I can get the behavior I
     want? Or better yet - has someone got a piece of code that already
     implements a command line with a buffer?



It seems you will be reinventing the (curses) wheel, and setting yourself
up to maintaining a version for each new terminal with its own unique
"up arrow key" encoding. Just do a few pragma imports, and you'll have
all the functionality you need to cope with any terminal type Unix can
throw at you.

There is an Ada binding to one of the curses packages around.
(i've also got one on my home page).

BTW would not character'Image (ch) have done what you attempted to do 
in your large case statement?

Dale