RE: join() and split() to respect string overload operations

On Mon, 07 Jun 2010, Paul LeoNerd Evans wrote:
> Now create a string-like object with well-behaved operator overload for
> concat, and observe you cannot still preserve the following identities:
> 
>   my $str = StringLike->new("Foo");
> 
>   substr( $str . "x", 0, len $str ) eq $str
>   substr( "x" . $str, 0, 1 ) eq $str
> 
>   substr( $str, 0, 1 ) . substr( $str, 1 ) eq $str

I don't quite get how this would not work as long as you also have a
well-behaved overload for 'eq' and '""'.  Or would these identities also be
broken:

   substr( $str . "x", 0, len $str ) eq "$str"
   substr( "x" . $str, 0, 1 ) eq "$str"
 
   substr( $str, 0, 1 ) . substr( $str, 1 ) eq "$str"

If these work, but yours don't, then I wouldn't consider the complete
set of overloads to be self-consistent.  If the these later identities
are broken as well, could you give an example of how to do it?

Cheers,
-Jan