Or you use closures to turn call-backs into iterators. Here I've altered the API a smidge because the original code used chdir() during the loop which is probably an unexpected side-effect. For anyone that is interested - Dominus is writing an excellent book on iterators and it includes a section on transforming recursive calls somewhat thusly. Here's a link to the book's web page (which you must all now go out and buy (when it is published)). BTW - this doesn't explain continuations at all - I'm just presenting a different perl5-accessible solution to the problem that tye posed.
my $find = find('', '');
while (my $file = $find->()) {
print join('/', @$file)."\n";
}
sub find {
my @todo = shift;
my @results;
return sub {
while (@todo and not @results) {
my $subdir = shift @todo;
$subdir = "." if ! defined $subdir or $subdir eq '';
$subdir .= "/" if $subdir =~ m{[^/]$};
my @files= ( glob("$subdir.*"), glob("$subdir*") );
for my $file ( @files ) {
next if $file =~ /\.\.?$/;
if( ! -l $file && -d _ ) {
push @todo, \ $file;
}
push @results, [ $subdir, substr($file,length($subdir)
+) ];
}
}
return shift @results;
};
}
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