Class templates and constructors -

templates great add features class, there problem constructors: works when template ctor , class (passed parameter) ctor have default form. (dpaste tester)

module main;  class cinternalmandatoryclass{}; class cimplementsomestuffs(t): t  if((is(t==class)/* & (haveadefaultctor!t) */)) {     private:     cinternalmandatoryclass fobj;     public:      void something1(){}     this(){fobj = new cinternalmandatoryclass;}     ~this(){delete fobj;} }  class csource1 {     int fa;     this(){fa = 8;} } class csource2 {     int fa;     this(){}     this(int a){fa = a;} }  class csourcewithsomestuffs1: cimplementsomestuffs!csource1 {     this()     {         assert(fobj !is null); // check cimplementsomestuffs ctor         assert(fa == 8); // check csource1 ctor     } }  class csourcewithsomestuffs2: cimplementsomestuffs!csource2 {     this(int a)     {         // need call csource2 ctor         assert(fobj !is null); // check cimplementsomestuffs ctor         assert(fa == 9); // check csource2 ctor, fails     } }  void main(string[] args) {     auto foo = new csourcewithsomestuffs1();     delete foo;     auto bar = new csourcewithsomestuffs2(9);     delete bar; } 

is possible call csource2 ctor in csourcewithsomestuffs2 ? if not, there trait test class have default constructor ?

you can build chain of super calls, forwarding constructor arguments:

in cimplementsomestuffs:

this(a ...)(a args) // formerly this() {     super(args);     // etc ... 

in csourcewithsomestuffs2:

this(int a) // this(a ...)(args), {     super(a);     // etc ...