How to create a vitual struct?

[bioinfornatics via Digitalmars-d-learn]

Hi,

I would like to create a virtual struct, i mean as Input Range.
You can create a new struct type and to be an input range. i know
that use duck typing :-)


In my case i would like to use duck typing if a stuct of any type
have an a given attribute. By exbample if at least on field as
@MyUDA

with this i could send any type of struct to a function

struct MyUDA {}

struct A {
  @MyUDA int a;
}


strct B {
  @MyUDA string b;
}


foo( A );
foo( B );


I hope that is enough clear.