!                                                                       Page 3
procedure eveplus_key 	! Redefine a key, saving old definition
	( new_pgm,	! Valid 1st argument for define_key builtin
	  default_key,	! Default keyname if user hasn't defined one
	  new_doc,	! Valid 3rd argument for define_key builtin
	  key_string )	! String containing name for user defined keys

! 1) Determine if we have a user specified key; if not, use default.
! 2) Save the present definition & doc. of the user specified key.
! 3) Do a define key on the new key information.

! A note on methods:

! We use a string argument for the variable name of the user specified key
! so that: 1) We can successfully pass it to this procedure if its not defined.
!          2) We can generate variables to hold the old key's info, avoiding
!             passing more arguments for these.

! We combine the string argument with string constants to form valid TPU
! statements which we then execute.  (Ha! We TPU programmers can limp
!                                     along without LISP very well thanks!)
on_error endon_error;
eveplus$x := default_key;	! default, to global variables; the variables
eveplus$x_string := key_string;	! Move arguments, which are local by
eveplus$x_old_pgm := 0;		! in and EXECUTE statement are all global.

! Determine if we have a user specified key; if not, use default.

if expand_name ( eveplus$x_string, variables ) <> eve$x_null then
    execute (	'if(get_info('+eveplus$x_string+',"type")=integer)then '
			+'eveplus$x:='+eveplus$x_string+';'
		+'else '
	  		+eveplus$x_string+':=eveplus$x;'
	+'endif;' );
else
	execute ( eveplus$x_string+ ':=  eveplus$x;' );
endif;

! Save the present definition & doc. of the user specified key
! one exists.

eveplus$x_old_pgm := lookup_key ( eveplus$x, program);

if (get_info ( eveplus$x_old_pgm, "type") = program) then
	execute( eveplus$x_string
		+'_doc := lookup_key ( eveplus$x, comment);'
		+eveplus$x_string
		+'_pgm := lookup_key ( eveplus$x, program);');
else
	execute( eveplus$x_string +'_doc := "~none~";');
endif;


! Do a define key on the new key information

define_key ( new_pgm, eveplus$x, new_doc,"eve$standard_keys" );
endprocedure