Antoine Pitrou wrote:
> Antoine Pitrou <pitrou@free.fr> added the comment:
> 
>> There were a number of patches to support sharing of data between 
>> unicode objects.  (By Larry Hastings?)  They were rejected because (a)  
>> they were complicated, and (b)  it was possible to provoke pathological 
>> memory retention.
> 
> Yes, it's the "lazy strings" patches by Larry Hastings (it was for str,
> not unicode, though). Issues are #1590352 and #1569040 (and perhaps
> others).
> 
> In any case, as I said, it is easy to switch back to the old
> representation, so I don't think it is an argument to block this patch.

That's not the case.

The patch breaks C API + binary compatibility for an essential Python
type - that's not something you can easily undo.