From: Jens Theisen (jens.theisen_at_[hidden])
Date: 2005-03-22 06:21:11
David Abrahams wrote:
> Jens Theisen <jens.theisen_at_[hidden]> writes:
>>My reference type is a simple reference, I want to implement an lvalue
>>iterator (at least in some cases).
>
> And why is it only single-pass?
>
>
>>I am trying to make a proxy iterator
>
> ^^^^^^^^^^^^^^
> What do you mean by that?
It is a class templated on a value_type to with implementations can be
attached (at run time). For example:
List< char > l = makeList(some_std_string) + makeList(some_char_array);
l.begin(), l.end() give you an iterator which type depends solely on the
value_type (char in this case), rather than the iterator types used as
backends (std::string::iterator and pointers). These iterators will
iterate over the std::string first and after this over the char array.
> I don't see why that would be incompatible with forward traversal. We
> don't even seem to have a requirement that a copy of an iterator
> compares equal with it. Perhaps we should; then you might be in
> trouble [Jeremy, Thomas, your thoughts?]
Oh, you're right. I somehow assumed that would be the case. However,
this is a requirement for Forward iterators, and iterator_faced gives
the forward_traversal_tag to Forward traversal iterators with reference
reference type. So it maybe a good idea to add this requirement.
> That shouldn't be slow if there's plenty of inlining.
The indirections are runtime indirections.
Best regards,
Jens