[Python-3000] Immutable bytes type and dbm modules

[Talin]

Nick Coghlan wrote:
> Martin v. Löwis wrote:
>> I don't think it needs to be a separate type,
>> instead, bytes objects could have a idem-potent
>> .freeze() method which switches the "immutable"
>> bit on. There would be no way to switch it off
>> again.
> 
> +1 here - hashable byte sequences are very handy for dealing with 
> fragments of low level serial protocols.
> 
> It would also be nice if b"" literals set that immutable flag 
> automatically - otherwise converting some of my lookup tables over to 
> Py3k would be a serious pain (not a pain I'm likely to have to deal with 
> personally given the relative time frames involved, but a pain nonetheless).


I'm also for an immutable bytes type - but I'm not so sure about 
freezing in place.

The most efficient representation of immutable bytes is quite different 
from the most efficient representation of mutable bytes.

Rather, I think that they should both share a common Abstract Base Class 
defining what you can do with immutable byte strings, but the actual 
storage of the bytes themselves should be implemented in the subclass.

-- Talin