gist to demonstrate querying methods for annotations (user defined attributes) in D.

getUserDefinedAttributes.d

import std.traits;
import std.stdio;

// A custom attribute:
struct Test
{
        bool enabled = true;
        int timeout = 5000;
}

class MyTest
{
        @Test
        void foo() {
                writeln("in foo()");
        }

	/// TODO: this does not work yet
        @Test
        void bar(int i) {
                writefln("in bar(%d)", i);
        }

	/// TODO: this does not work yet
        @Test(false, 4000)
        void baz() {
                writefln("in baz()");
        }
}

/// determine if the type X is contained in T...
template hasTag(X, T...) {
        //pragma(msg, T);
        static if (T.length) {
                static if (is(T[0] : X)) {
                        enum hasTag = true;
                } else {
                        enum hasTag = hasTag!(X, T[1 .. $]);
                }
        } else {
                enum hasTag = false;
        }
}

auto invokeTestMembers(T)(T type) {
        foreach (fn; __traits(allMembers, T)) {
                debug writeln("fn = ", fn);
                if (hasTag!(Test, __traits(getAttributes, __traits(getMember, type, fn) ))) {
                        debug writeln("\ttest method!");
                        static if (__traits(compiles, __traits(getVirtualFunctions, type, fn)[0]())) {
                                __traits(getVirtualFunctions, type, fn)[0]();
                        }
                }
        }
}

void main()
{
        auto myTest = new MyTest();
        invokeTestMembers(myTest);
}