Jack Stouffer and I have been working on a pull request for Phobos to enable runtime dispatch for field and property access:
    https://github.com/D-Programming-Language/phobos/pull/4070
(It's useful when directly porting code from dynamic languages like Python.)

Working with fields in this fashion is pretty easy, but I've hit a snag for property methods: if even one of the available property methods is impure, unsafe, etc., then the dispatch function must also be impure/unsafe/whatever.

In order for the dispatch function to be usable in pure/@safe/etc. code, it needs to filter out those property methods which are not. This is simple enough - except that *which* attributes are required cannot be inferred from the context; it must be explicitly specified by the user of the dispatch template - somehow...

A naive way to do it would be this:

    template example(string attrs = "pure @safe nothrow @nogc")
    {
        mixin("void example() " ~ attrs ~ " { /* do something */ }");
    }

Which could then be used like this:

    example!"pure @safe @SomeUDA"();

That's pretty ugly though, since it requires that all template functions with explicit attribute control be implemented as string mixins.

Is there a better way to do this? If not, I think consideration should be given (long-term) to adding an "attribute set" construct as a new type of template parameter.