'partial' keyword in C# is very good for project , what's the same thing in D?

[FrankLike via Digitalmars-d]

>> Partial classes are used in C# wherever you need to combine 
>> auto-generated code and user code into a single class.  So, 
>> the Windows GUI builder does it placing all the GUI component 
>> construction and property setting in one file, and allowing 
>> the user to only have to see/edit the application level code 
>> in another file.  Likewise LINQ to SQL generates a custom 
>> DataContext child class, and the user can optionally create a 
>> 2nd file with the partial class to extend it.
>
>> R
>
> The same thing in D should be done,now.Otherwise，no big 
> projects can be very easily  done like C#. Add another 
> keyword,and update the compiler.
>
> FrankLike