!return(4)

NAME

!return, !abort - Exit macro

SYNOPSIS

!return [n]
!abort

DESCRIPTION

The !return directive causes the current macro to exit with a TRUE status, either returning to the caller (if any) or to interactive mode. If an argument n is specified then the return status is determined by the value of n.

!abort has the same effect as !return only returning a FALSE status, this halts the execution of any calling macros. !abort is generally used in conjunction with !bell(4) to sound an audio alarm if the user has performed an invalid action.

EXAMPLE

The following example checks the monitor type. If the monitor is monochrome then the message is displayed. If the monitor type is not mono no message is displayed.

;	Check the monitor type and set %mtyp 

!if &not &seq $TERM "MONO" 
    set-variable %mtyp 1 
    !return 
!else 
    set-variable %mtyp 2 
!endif 
ml-write "You are on a MONOCHROME machine (if you are color blind)" 

The following example is shows the logic of the !return directive:-

; !return example 
define-macro i-will-return 
    ml-write "you will see me" 
    !return 
    ml-write "you wont see me" 
!emacro 

define-macro test-return 
    ml-write "you will see me" 
    i-will-return 
    ml-write "you will see me" 
!emacro 

Similarly, for the !abort directive

; !abort example 
define-macro i-will-abort 
    ml-write "you will see me" 
    !abort 
    ml-write "you wont see me" 
!emacro 

define-macro test-abort 
    ml-write "you will see me" 
    i-will-abort 
    ml-write "you wont see me" 
!emacro 

For the last two examples above, all the "will"s are displayed and none of the "wont"s are.

SEE ALSO

define-macro(2), !bell(4), !if(4), !goto(4).

(c) Copyright JASSPA 1999
Last Modified: 1999/08/24
Generated On: 1999/12/01