That is no a split then, that is a pattern match. The problem remains that a line like 'a::b:: c' will match according to your rules but the result will be 'a', ':b', 'c'. You can do this easily with recursion:

my @split_bits = qw( : :: \s+ );

my @result = wierd_split( 'foo:bar::baz  boo:foo::bar::baz', \@split_b
+its );
print "Got $_\n" for @result;

sub wierd_split {
    my ( $str, $to_do, $got ) = @_;
  return (@$got, $str) unless @$to_do;
    my $next_split = shift @$to_do;
    print scalar @$to_do, " splitting '$str' on '$next_split'", "\n";
    my ( $want, $next ) = $str =~ m/(.*?)$next_split(.*)/m;
    print "'$want' '$next'\n";
    push @{$got}, $want;
    # and now for a little recursion
    wierd_split( $next, $to_do, $got ) if $want;
}
__DATA__
2 splitting 'foo:bar::baz  boo:foo::bar::baz' on ':'
'foo' 'bar::baz  boo:foo::bar::baz'
1 splitting 'bar::baz  boo:foo::bar::baz' on '::'
'bar' 'baz  boo:foo::bar::baz'
0 splitting 'baz  boo:foo::bar::baz' on '\s+'
'baz' 'boo:foo::bar::baz'
Got foo
Got bar
Got baz
Got boo:foo::bar::baz
[download]

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

Here's a non-recursive function:

sub wierd_split (\@@) {
    my $regex = shift;
    local $_  = @_ ? shift : $_;

    my    @res;
   ($res [@res],  $_) = split shift @$regex, $_, 2 while @$regex && le
+ngth;
    push  @res => $_ if length;

    @res
}

print "Got $_\n" for wierd_split @{[':', '::', '\s+']} => 'foo:bar::ba
+z frog';
__END__
Got foo
Got bar
Got baz
Got frog
[download]

Adding all the funny stuff of split, like using it in void context, its third parameter, or captures in the regex is left as an exercise for the reader.

Abigail