Is it possible to use an UDA to generate a struct inside a class ?

[Ali Çehreli via Digitalmars-d-learn]

On 12/30/2014 09:42 AM, Basile Burg wrote:

 > Can a descriptor be created using my "attribute" ? How ?

Here is a quick and dirty solution:

import std.string;

struct PropertyDescriptor
{
     string type;
     string name;

     string memberName() @property const
     {
         return name ~ "_";
     }

     string definition() @property const
     {
         return format("%s %s;", type, memberName);
     }

     string getter() @property const
     {
         return format("%s %s() @property const { return %s; }",
                       type, name, memberName);
     }

     string setter() @property const
     {
         return format("void %s(%s value) @property { %s = value; }",
                       name, type, memberName);
     }
}

unittest
{
     const descr = PropertyDescriptor("int", "foo");

     assert(descr.memberName == "foo_");
     assert(descr.definition == q{int foo_;});
     assert(descr.getter == q{int foo() @property const { return foo_; }});
     assert(descr.setter ==
            q{void foo(int value) @property { foo_ = value; }});
}

struct Property
{
     PropertyDescriptor[] properties;

     string propertyCode() @property const
     {
         string result;

         foreach (property; properties) {
             result ~= property.definition ~ property.getter ~ 
property.setter;
         }

         return result;
     }
}

string propertyInjections(T)()
{
     string result;

     foreach (attr; __traits(getAttributes, T)) {
         static if (is (typeof(attr) == Property)) {
             result ~= attr.propertyCode;
         }
     }

     return result;
}

@Property([ PropertyDescriptor("int", "i"),
             PropertyDescriptor("double", "d") ])
class C
{
     mixin (propertyInjections!C);
}

void main()
{
     auto c = new C();
     c.i = 42;
     assert(c.i == 42);
}

Ali