On 05/27/2015 05:30 PM, Steven Schveighoffer wrote:
On 5/27/15 9:11 AM, "Simon =?UTF-8?B?QsO8cmdlciI=?=
<simon.buer...@rwth-aachen.de>" wrote:
On Wednesday, 27 May 2015 at 14:58:39 UTC, drug wrote:
Do you want to dynamically change priority?
Actually yes. In my actual code I am not using a RedBlackTree but my own
Container (a heap with the possibility to modify elements inside), which
is notified when prio changes so it can do a (local) reordering.
It would be a very bad idea to change prio if the RBTree is constructed
already (and if this works).
Why prio is outside of your predicate?
Well, how would I get it into the lambda? In C++ I would use a
comparision class, and the constructor of the container would take an
instance of that class. But D's RedBlackTree-constructor does not take
such a (run-time) argument. And I dont see a way to get prio into the
predicate, which is a template-argument.
This is true, RedBlackTree does not take a functor as a parameter to the
constructor, it just uses an alias.
This should work if your RedBlackTree is scoped inside a function where
the data exists. But at the time of declaration inside the class, the
instance of prio doesn't exist, so you can't alias it.
It would be a good enhancement I think to add support for function objects.
-Steve
Also, apart from missing implementation, there is no good reason why the
code given should not work, is there? I think nested template
instantiation should work in all scopes. (Of course, there is the issue
that nested structs are somewhat arbitrarily not given a context pointer
when declared within a class/struct, so this might be a little
inconsistent in case it also works for structs, no question for classes
though: just instantiate as nested class.)
