The redo
command restarts the loop block without evaluating the conditional again. The continue
block, if any, is not executed. If the LABEL is omitted, the command refers to the innermost enclosing loop. Programs that want to lie to themselves about what was just input normally use this command:
# a simpleminded Pascal comment stripper
# (warning: assumes no { or } in strings)
LINE: while (<STDIN>) {
while (s|({.*}.*){.*}|$1 |) {}
s|{.*}| |;
if (s|{.*| |) {
$front = $_;
while (<STDIN>) {
if (/}/) { # end of comment?
s|^|$front\{|;
redo LINE;
}
}
}
print;
}
redo
cannot be used to retry a block that returns a value such as eval {}
, sub {}
, or do {}
, and should not be used to exit a grep() or map() operation.
Note that a block by itself is semantically identical to a loop that executes once. Thus redo
inside such a block will effectively turn it into a looping construct.
See also "continue" for an illustration of how last
, next
, and redo
work.