secure const and

[Jason House]

Fawzi Mohamed wrote:

> I have tried to move part of this argument to the wiki.
> I have created a page at
> 
>   http://www.prowiki.org/wiki4d/wiki.cgi?TransitiveConst
> 
> feel free to add to it.
> 
> My main point is that I like Stevens proposal, but I think it should be
> seen as a hole to implement *secure* relaxations of the const concept,
> and so it should be clearly marked as a hole not to be used unless
> absolutely needed (and that will be in low level libraries).
> 
> The secure abstractions are secure enough to be allowed also in pure
> functions and invariant data structures, without breaking anything
> (only extension 2 adds a constraint more to the optimizations allowed,
> namely that copied data should be synchronized, but as I describe it
> still a very well behaved extension).
> 
> So I want that even pure functions have access to these mutable parts
> of the object, and if something bad happens the fault is obviously the
> fault of the programmer that used the hole in const in a bad way.
> This will make pure function more flexible, faster, and more likely to
> be written and used, something from which everybody should profit.
> 
> I think that I identified all reasonable use of mutable state in a
> const object, if you think I missed something, please add it.
> 
> As I say in the wiki also haskell (a language that considers
> provability quite important) has an uncontrolled hole (unsafePerformIO)
> that *is* used in special cases and it is the responsibility of the
> coder to make sure that it is used correctly. Also the monads laws are
> not verified by the compiler, it is just assumed that the implementor
> wrote them correctly.
> 
> Fawzi

Any way to add a table of contents?

I'd also hope that the page would be restructured to give people the
opportunity to talk about the pros of verious methods without arguing... 
Maybe something like a background section.

Of course, then there can be a few proposal sections where arguing can be
rampant :)  There should probably be a separate section for bicycle shed
discussions.