How to break const

[deadalnix]

Le 20/06/2012 13:58, Timon Gehr a écrit :
>>> Clarification: 'const' means 'const'. No other qualifiers.
>>>
>>> There is no 'const' in that example code. 'immutable' obviously needs to
>>> be transitive regardless of the particular interpretation of 'const'.
>>>
>> const means: maybe immutable.
>
> Or maybe mutable. Therefore, interpretation '2.'
>
>> Thus const needs to be transitive too.
>
> Wrong. This is the (A==>B) ==> (B==>A) fallacy, where
>
> A: 'const' is transitive
> B: 'const' references cannot modify 'immutable' data
>

I understand the difference. It can change the legality of some calls, 
that is true (and probably it is better). But it doesn't change the need 
for a frame pointer's qualifier (mandatory to ensure immutability 
transitivity).

To benefit of the extra freedom granted by B, what could be the casts 
safely allowed on the delegate ? I understand your point, but fail to 
find any way to make it work in practice.