RE: Re: Mutable Bytes

Greg Ewing wrote:

> Mark Hahn <[email protected]>:
> 
> > The reason I changed it to check the immutable bit is that the 
> > built-in types aren't really immutable until they are 
> initialized.  An 
> > Int object will effectively change value when it goes from 
> having no 
> > value to having a value.
> 
> It would be better to check the immutable bit in the hash 
> functions of the objects concerned. It's only for those 
> particular object types that the immutable bit implies 
> usability as a key and vice versa.
> 
> In the general case, the immutable bit being set is neither 
> necessary nor sufficient for an object to be usable as a key. 
> The comparison function might depend on state which doesn't 
> change, even though other parts of the object's state can 
> change. Conversely, it might depend on the state of other 
> objects referenced by the object which can change, even 
> though the object itself is marked as immutable.
> 
> So tying this to the immutable bit in general for all objects 
> is wrong, IMO.

I understand.  The list, for example, can be checked for equality and yet it
is dependent on other objects.  Do you think I should just pull the
immutability check?