!goto(4)

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NAME

!goto - Unconditional labeled jump
!tgoto - Conditional labeled jump

SYNOPSIS

!goto label
...
*label

!tgoto condition label
...
*label

DESCRIPTION

Flow can be controlled within a MicroEmacs macro using the !goto directive. It takes as an argument a label. A label consists of a line starting with an asterisk (*) and then an alphanumeric label. Only labels in the currently executing macro can be jumped to, trying to jump to a non-existing label terminates execution of a macro. labels may be located at any position within the macro (forwards or backwards from the !goto).

A conditional jump may be implemented with a !tgoto, this takes an additional argument condition, which may be a literal numeric value, a variable or an evaluated expression (see Variable Functions). If the condition evaluates to TRUE (or non-zero) then the branch is taken and control continues from the label.

!tgoto is an ideal replacement for !while(4) and !repeat(4) where nested loops are required.

EXAMPLE

For example, create a block of DATA statements for a BASIC program:

        insert-string "1000 DATA " 
        set-variable %linenum 1000 
*nxtin 
        screen-update           ;make sure we see the changes 
        set-variable %data @ml"Next number: " 
        !if &equal %data 0 
            !goto finish 
        !endif 
        !if &greater $curcol 60 
            2 backward-delete-char 
            newline 
            set-variable %linenum &add %linenum 10 
            insert-string &cat %linenum " DATA " 
        !endif 
        insert-string &cat %data ", " 
        !goto nxtin 
*finish 
        2 backward-delete-char 
        newline

Not that any of us are writing basic programs these days !!

NOTES