On 2010-10-06 20:21, Nevin Liber wrote:
Although [references aren't] the most important case for me, it has its own section in the documentation, and I will probably be using lots of these.
Why? What is the advantage over using a raw pointer?
None at this time. It's just that an optional<T&> exactly does what everyone usually does with null-pointers and stuff. I thought it might be clearer and less prone to error.
What also doesn't seem right to me is that, e.g.,
struct A { int a; double b; double c; std::string d; };
struct B { boost::optional< int> a; boost::optional< double> b; boost::optional< double> c; boost::optional< std::string> d; };
What bit pattern can be used for an int which says it hasn't been set?
In this particular example I'm showing the space efficiency of different classes (see http://article.gmane.org/gmane.comp.lib.boost.devel/209212), I'm not saying int should have a certain bit pattern for "unset". I'm merely saying that due to the extra boolean and padding, sizeof(B) grows.
Optional models "the variable is not set." You want something different. Why not just create a different class to model what you want?
I think I know what optional models, and it is clearly what I want. However, I would like to have space-efficient ones. Cheers, Rutger