Tagged location in the source code
Labels are used in Perl 6 to tag loops so that you can specify the one you want to jump to with statements such as
last. You can use it to jump out of loops and get to outer ones, instead of just exiting the current loop or going to the statement before.
USERS: # the labelfor ->say USERS.^name; # OUTPUT: «Label␤»
Those label are objects of type
Label, as shown in the last statement. Labels can be used in any loop construct, as long as they appear right before the loop statement.
my = 0;my = 0;my = '';A: while ++ < 2say ; # OUTPUT: «A1B1A1A2»
Putting them on the line before the loop or the same line is optional.
Labels must follow the syntax of ordinary identifiers, although traditionally we will use the latin alphabet in uppercase so that they stand out in the source. You can use, however, other alphabets like here:
駱駝道: while True
Not terribly useful, returns the name of the defined label:
A: while True
Begin the next iteration of the loop associated with the label.
MY-LABEL:for 1..10# OUTPUT: «5 6 7 8 9 10 »
Repeat the same iteration of the loop associated with the label.
my = False;MY-LABEL:for 1..10# OUTPUT: «1 2 3 4 5 5 6 7 8 9 10 »
Terminate the execution of the loop associated with the label.
MY-LABEL:for 1..10# OUTPUT: «1 2 3 4 5 »