On 8 Mar 2011, at 09:36, Sebastian Redl wrote:
On 07.03.2011 20:27, SATAN66613 wrote:
on 07.03.2011 at 13:48 Christopher Jefferson wrote :
So users of a expression-template based xint would need to know about proto::deep_copy? Also, I would expect these problems to become more serious in C++0x code, because users will probably write expressions like: auto i = x + y; Which would be fine for built-in types, and introduce bugs if x or y was an xint::integer, using proto. could we prevent this misusage by making copy constructor of the expression class private (possibly never implementing it)? Since we're talking C++0x, making it =delete would be the right thing. And yes, that should prevent the misuse. Come to think of it, I can't think of any reason why that wouldn't work.
That was my first thought. I'm not particularly knowledgable about boost::proto, so I don't know how much disabling the copy constructor would limit the functionality. If it didn't create too many problems it is probably the way to go, possibly with a 'clone' function if that would be useful for people really want to make a copy, and know what they are doing. Chris