struct sta­tic ini­tial­izer method apply to UDA

[learnfirst1]

my question is how to easy use struct sta­tic ini­tial­izer 
method with UDA.

Fake code:

struct DbColumn {
          string name;
	bool	unique ;
	bool	signed ;
	bool	nullable ;
}

struct Order {
	uint id;
	
	@DbColumn({ .nullable= true}) // not working
	string order_id;

	@DbColumn({ :nullable= true}) // not working
	string order_time;

	@DbColumn(nullable= true) // not working
	string order_time;
}