http://d.puremagic.com/issues/show_bug.cgi?id=4000
Summary: Function pointer/delegate covariance Product: D Version: future Platform: All OS/Version: All Status: NEW Keywords: rejects-valid Severity: enhancement Priority: P2 Component: DMD AssignedTo: nob...@puremagic.com ReportedBy: bearophile_h...@eml.cc --- Comment #0 from bearophile_h...@eml.cc 2010-03-22 07:11:14 PDT --- This page about C#: http://msdn.microsoft.com/en-us/library/ms173174%28VS.80%29.aspx contains this working C# code: class Mammals {} class Dogs : Mammals {} class Program { public delegate Mammals HandlerMethod(); public static Mammals FirstHandler() { return null; } public static Dogs SecondHandler() { return null; } static void Main() { HandlerMethod handler1 = FirstHandler; HandlerMethod handler2 = SecondHandler; } } This is a possible translation to D2: class Mammals {} class Dogs : Mammals {} alias Mammals function() HandlerMethod; Mammals function() handler; Mammals FirstHandler() { return null; } Dogs SecondHandler() { return null; } void main() { HandlerMethod handler1 = &FirstHandler; HandlerMethod handler2 = &SecondHandler; // line 9, err handler = &SecondHandler; // line 10, err } But the D2 code gives two compile errors: test.d(9): Error: cannot implicitly convert expression (& SecondHandler) of type Dogs function() to Mammals function() test.d(10): Error: cannot implicitly convert expression (& SecondHandler) of type Dogs function() to Mammals function() It can be positive for the D type system to accept this code too. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------