preparing for const, final, and invariant

[Dave]

Walter Bright wrote:
> Bill Baxter wrote:
>> That makes sense to me too.  If you don't say anything it's 'scope 
>> const final'.  But if you do specify something then it's only that.
> 

So the new 'in' would be the default if not specified, right?

> Right. There are too many qualifies to do otherwise.
> 
>> I'm not wild about the aesthetics of !const for parameters, and even 
>> less wild about the possibility that !const could become common idiom 
>> for modifiable parameters.  If it's a common way to pass a parameter, 
>> then there should be a way to express the attribute positively (like 
>> "mutable" or "variable" or "inout") in terms of what it does do, 
>> rather than what it doesn't.
> 
> Uh, I think you put a finger on just where I was getting a bad feeling 
> about !const. It's generally confusing to use negatives as attributes, 
> i.e., having state variables named:
>     "notFull"
> is a bad idea.
> 
> I'm at the moment thinking we should just bite the bullet and introduce 
> 'mutable' as a keyword.

A little late and FWIW, but this all sounds great to me!