Rope PMC (was Re: Why has pbc_to_exe become unusable?)

[Patrick R. Michaud]

On Thu, Apr 22, 2010 at 12:59:35PM -0400, Will Coleda wrote:
> The original thread here was "string concatenation is slow". Sounds
> like RSA is a good fit for that, and everything else can be done
> outside of core and copied back in if we like it.

RSA is a good fit only if it's also possible to quickly concatenate
RSA's.  I'm not sure that's currently the case, although perhaps the
splice opcode works for this.

In the case of POST::Compiler, most "concatenations" occur on CodeString
PMCs through the .emit() method.  It's certainly okay to redesign emit() 
internally so that it maintains the string as some other structure,
as long as when we ultimately request get_string() we get the expected
result.  CodeStrings also currently expect to be 'isa String' -- that may
want to be changed into 'does string' at some point, but doing so
would likely also have a big impact on lots of existing :multi() subs.

Pm