use Perl

TextMate registers a handler for the txmt:// URL scheme that can be used to send it to a particular file, line and column (you can read more about that here).

Mac OS has /usr/bin/open which allows an arbitrary URL (or file or application) to be opened from the command line.

The Perl debugger recognises a function watchfunction, defined in ~/.perldb and calls it for every line it executes.

Throwing all those ingredients together gives us TextMate::JumpTo - a module to remotely control TextMate's current location - and this ~/.perldb file which tells the debugger to sync its position with TextMate:

use TextMate::JumpTo qw(jumpto);

sub afterinit {
    $trace |= 4;    # Enable watchfunction

    # Needed to work out where filenames are relative to
    chomp( $base_dir = `pwd` );
}

sub watchfunction {
    my ( $package, $file, $line ) = @_;
    local $trace = 0;
    if ( $file =~ /^\(eval\s+\d+\)\[(.+?):(\d+)\]/ ) {
        $file = $1;
        $line += $2 - 1;
    }
    $file = File::Spec->rel2abs( $file, $base_dir );
    jumpto( file => $file, line => $line, bg => 1 )
      if substr( $file, 0, length( $base_dir ) ) eq $base_dir;
}

Now I just debug normally and any time I want to see the code around the current line I switch to the editor and there it is. It's not quite full editor integration but it immediately makes my life a lot easier.