UDA and mixins

[Oleg via Digitalmars-d-learn]

I want to write mixin template, what past and/or change some code 
in class. Mixin must get all functions with user defined 
attribute and past fields for example. It should looks like this

struct FooPasted(Args...){}
class A
{
mixin foo;

void func1() @mark { ... }
void func2( int x, string a ) @mark { ... }

}

Question 1:

I get members with @mark via this template:

template filterMembers(alias F,T,string[] list=[])
if( is( T == class ) || is( T == struct ) )
{
    static if( list.length > 0 ) enum filterMembers = impl!list;
    else enum filterMembers = impl!([__traits(allMembers,T)]);

    string[] impl(string[] names)() @property
    {
        static if( names.length == 0 ) return [];
        else static if( names.length == 1 )
        {
            enum n = names[0];
            static if( __traits(compiles,__traits(getMember,T,n)) 
)
                return F!(__traits(getMember,T,n)) ? [n] : [];
            else return [];
        }
        else return impl!(names[0..$/2]) ~ impl!(names[$/2..$]);
    }
}

an easier way to do this exists? something like 
__traits(UDAMembers,T,mark)

Question 2:

Can i change or remove exists code via mixin?

definition

class X
{
  mixin foo;
  void func() @impl;
}

change to

class X
{
  void func() { ... implement by foo ... }
}