On Mon, 31 Mar 2014 18:58:30 +0000, anonymous wrote: > Hi, > I'm new to D and played a bit with templates and delegates. > Now i discovered some behaviore that i don't understand. Can somebody > explain me why i get two different outputs? > > > import std.stdio; > > > interface A(T){ > bool GetBool(); > T getT(); > } > > class C:A!(double){ > override bool GetBool(){ > return false; > } > override double getT(){ > return 1; > } > } > > void mwriteln(T)( A!T delegate() dg){ > writeln(dg().getT()); > } > > void main() > { > auto c = new C(); writeln(c.getT()); mwriteln!double({return new > C();}); > }
Looks like a bug. Here's a cleaned-up test case: ----------------------------------------------------------- interface A(T) { T getT(); } class C : A!double { double getT(){ return 1; } } void mwriteln(T)(A!T delegate() dg) { import std.stdio; auto a = dg(); writeln("Checkpoint 1"); assert(a !is null); writeln(a); writeln("Checkpoint 2"); } void main() { import std.traits; static assert(isImplicitlyConvertible!(C, A!double)); mwriteln!double({return new C();}); } ----------------------------------------------------------- Backtrace: ----------------------------------------------------------- Program received signal SIGSEGV, Segmentation fault. #0 0x000000000042ac8c in _d_interface_cast () #1 0x0000000000427ec6 in std.format.__T11formatValueTS3std5stdio4File17LockingTextWriterTC4test8__T1ATdZ1ATaZ.formatValue () () #2 0x0000000000427e23 in std.format.__T13formatGenericTS3std5stdio4File17LockingTextWriterTC4test8__T1ATdZ1ATaZ.formatGeneric () () #3 0x0000000000427d29 in std.format.__T14formattedWriteTS3std5stdio4File17LockingTextWriterTaTC4test8__T1ATdZ1AZ.formattedWrite () () #4 0x0000000000427871 in std.stdio.File.__T5writeTC4test8__T1ATdZ1ATaZ.write() () #5 0x00000000004277d5 in std.stdio.__T7writelnTC4test8__T1ATdZ1AZ.writeln () () #6 0x000000000042771f in test.__T8mwritelnTdZ.mwriteln() () #7 0x00000000004276a9 in D main () #8 0x000000000042b61c in rt.dmain2._d_run_main() () #9 0x000000000042b576 in rt.dmain2._d_run_main() () #10 0x000000000042b5dc in rt.dmain2._d_run_main() () #11 0x000000000042b576 in rt.dmain2._d_run_main() () #12 0x000000000042b4f7 in _d_run_main () #13 0x0000000000429c5f in main () -----------------------------------------------------------