RE: [boost] [smart_ptr] const-correctness as function argument

From: Rozental, Gennadiy (gennadiy.rozental_at_[hidden])
Date: 2002-10-02 13:27:30

> Are those just a few exceptions?  I think I read in D&E a 
> discussion that const is almost useless (but I can't locate 
> D&E now, so I can't look it up).  Searching for material on 
> this now, I find a reference to an article by Andrew Koenig 
> (How much does const promise? - C++ Report/1997) that 
> apparently seems to make the same point but I don't know 
> because I haven't read the article.  Another page I found 
> gave an example that the compiler must make sure that "this" 
> is not saved in any of the constructors as this would allow 
> the object to access itself non-constly.  This means the 
> compiler must know the content of the constructor with which 
> your optimization candidate was initialized, and the content 
> of the constructors used in the initializer list of that 
> constructor for each the object's members, etc etc 
> recursively, before considering optimizations.  Maybe I'm 
> just talking nonsense, but it was just my (perhaps-mistaken) 
> understanding that compilers cannot really do optimizat!
> ions based on const, without a lot of work that is not worth 
> it just for this optimization capability.  Anyway, this is 
> all I can say on the subject :)

I second this.  I also beleive that due to presence in a language const_cast
and mutable in majority of the cases compiler is not capable of any
optimization based in constness.

Gennadiy.