List classes in a module at CT

listclasses.d

alias Identity(alias sym) = sym;

template ClassesInModule(alias mod)
{
    import std.typetuple : Filter, staticMap;

    enum isAccessibleClassDeclaration(string member) = __traits(compiles, __traits(getMember, mod, member)) &&
        is(Identity!(__traits(getMember, mod, member)) == class);

    alias LookupMemberType(string member) = Identity!(__traits(getMember, mod, member));

    alias ClassesInModule = staticMap!(LookupMemberType, Filter!(isAccessibleClassDeclaration, __traits(allMembers, mod)));
}

import std.stream;
alias ClassesInStdStream = ClassesInModule!(std.stream);
pragma(msg, ClassesInStdStream);