Does this syntax:

Code: Select all

class Foo
{
  template <int Times = 1>
  struct Nested
  {
    typedef Bar type;
  }
}


Could replace the currently explicit one:

Code: Select all

class Foo;
template <int Times>
struct ei_nested<Foo, Times>
{
    typedef Bar type;
};


There are two advantages:
[*] Easier to access - Foo::Nested<Times> instead of internal::ei_nested<Foo, Times>::type
[*] Easier to maintain

As you might see, the style was taken from from C++ Allocator concept rebind<U>::other
Do you think it should be used in future Eigen versions?

hm, ei_nested was for Eigen2 which is rather outdated! It does not exist in Eigen3.x. See also this entry for some old discussions on this topic: http://eigen.tuxfamily.org/bz/show_bug.cgi?id=111

ggael wrote:hm, ei_nested was for Eigen2 which is rather outdated! It does not exist in Eigen3.x. See also this entry for some old discussions on this topic: http://eigen.tuxfamily.org/bz/show_bug.cgi?id=111

Your claims conflict with this page: (something doesn't making sense for me)
http://eigen.tuxfamily.org/index.php?ti ... umentation

If this page is outdated too, what is the correct way now?

oh, I was not aware of this page, and indeed it is completely outdated! In the default branch, you should use internal::nested_eval<XprType,N>::type.

ggael wrote:oh, I was not aware of this page, and indeed it is completely outdated! In the default branch, you should use internal::nested_eval<XprType,N>::type.

Please notice that the top two links in this wiki page are invalid. IMHO, they should refer to:
http://eigen.tuxfamily.org/dox-devel/To ... nType.html

Thanks!