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digitalmars.D.learn - Anonymous nested class of problems

reply =?iso-8859-2?B?VG9tZWsgU293afFza2k=?= <just ask.me> writes:
I was playing with what makes the Javists proud, but stumbled over this:

class M {
     this(byte a) { _a = a; }
     byte _a;
     byte a() { return _a; };

     static m = new class(4) M {
         this(byte a) { super(a); }
         override byte a() { return 3+_a; }
     };
}

Error: class test.M.__anonclass10 has forward references
Error: no constructor for __anonclass10

Is this a compiler bug? There's no reason why the above shouldn't compile,  
no?


But that's not all, when I mark my class immutable...

immutable class M {
     this(byte a) { _a = a; }
     byte _a;
     byte a() { return _a; };
}

void main() {
     auto m = new class(4) M {
         this(byte a) { super(a); }
         override byte a() { return 3+_a; }
     };
}

... the compiler says: cannot implicitly convert expression (this) of type  
immutable(M) to test.M.
Same story for const classes. Again, compiler bug?


Tomek
Dec 12 2009
next sibling parent reply =?iso-8859-2?B?VG9tZWsgU293afFza2k=?= <just ask.me> writes:
Dnia 12-12-2009 o 13:09:49 Tomek Sowi=F1ski <just ask.me> napisa=B3(a):


 Error: no constructor for __anonclass10


This one seems to be unrelated to anonymous stuff.

class M {
     this(byte a) { _a =3D a; }
     byte _a;
     byte a() { return _a; };

     static m =3D new M(3);
}

I get: Error: no constructor for M.


Tomek
Dec 12 2009
parent reply div0 <div0 users.sourceforge.net> writes:
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Tomek Sowi�ski wrote:

 Dnia 12-12-2009 o 13:09:49 Tomek Sowi�ski <just ask.me> napisa�(a):
 

 Error: no constructor for __anonclass10


 
 This one seems to be unrelated to anonymous stuff.
 
 class M {
     this(byte a) { _a = a; }
     byte _a;
     byte a() { return _a; };
 
     static m = new M(3);
 }
 
 I get: Error: no constructor for M.
 
 
 Tomek


Well for this one, you're doing it wrong. You want:

class M {
    this(byte a) { _a = a; }
    byte _a;
    byte a() { return _a; };

    static M m;

    static this() {
        m = new M(3);
    }
}

- --
My enormous talent is exceeded only by my outrageous laziness.
http://www.ssTk.co.uk
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Dec 12 2009
parent reply =?utf-8?B?VG9tZWsgU293acWEc2tp?= <just ask.me> writes:
Dnia 12-12-2009 o 15:00:56 div0 <div0 users.sourceforge.net> napisa=C5=82=
(a):


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 Tomek Sowi=C3=B1ski wrote:

 Dnia 12-12-2009 o 13:09:49 Tomek Sowi=C3=B1ski <just ask.me> napisa=C2=




=B3(a):

 Error: no constructor for __anonclass10


 This one seems to be unrelated to anonymous stuff.

 class M {
     this(byte a) { _a =3D a; }
     byte _a;
     byte a() { return _a; };

     static m =3D new M(3);
 }

 I get: Error: no constructor for M.


 Tomek


 Well for this one, you're doing it wrong. You want:

 class M {
     this(byte a) { _a =3D a; }
     byte _a;
     byte a() { return _a; };

     static M m;

     static this() {
         m =3D new M(3);
     }
 }


So it's the same when I get the "non-constant expression..." error and  =

have to put in static ctors? Then what's with the "no constructor for M"=
?


Tomek
Dec 12 2009
parent div0 <div0 users.sourceforge.net> writes:
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Hash: SHA1

Tomek Sowiński wrote:

 Dnia 12-12-2009 o 15:00:56 div0 <div0 users.sourceforge.net> napisał(a):
 

 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1

 Tomek Sowiñski wrote:

 Dnia 12-12-2009 o 13:09:49 Tomek Sowiñski <just ask.me> napisa³(a):


 Error: no constructor for __anonclass10


 This one seems to be unrelated to anonymous stuff.

 class M {
     this(byte a) { _a = a; }
     byte _a;
     byte a() { return _a; };

     static m = new M(3);
 }

 I get: Error: no constructor for M.


 Tomek


 Well for this one, you're doing it wrong. You want:

 class M {
     this(byte a) { _a = a; }
     byte _a;
     byte a() { return _a; };

     static M m;

     static this() {
         m = new M(3);
     }
 }


 
 So it's the same when I get the "non-constant expression..." error and
 have to put in static ctors?


Yes I think.


 Then what's with the "no constructor for M"?


Don't know.

It's best not to read too much into DMDs error messages, they leave a
lot to be desired.

- --
My enormous talent is exceeded only by my outrageous laziness.
http://www.ssTk.co.uk
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Dec 12 2009
prev sibling parent reply =?iso-8859-2?B?VG9tZWsgU293afFza2k=?= <just ask.me> writes:
Dnia 12-12-2009 o 13:09:49 Tomek Sowi=F1ski <just ask.me> napisa=B3(a):


 But that's not all, when I mark my class immutable...

 immutable class M {
      this(byte a) { _a =3D a; }
      byte _a;
      byte a() { return _a; };
 }

 void main() {
      auto m =3D new class(4) M {
          this(byte a) { super(a); }
          override byte a() { return 3+_a; }
      };
 }

 ... the compiler says: cannot implicitly convert expression (this) of =


 =


 type immutable(M) to test.M.
 Same story for const classes. Again, compiler bug?


It's not only about anonymous classes. Take a look at this:

immutable class M {
     this(int a) { _a =3D a; }
     int _a;
     int a() { return _a; }
}

immutable class PodM : M {
     this(int a) { super(a); }
     override int a() { return 3+_a; }
}

void main() {
     auto m =3D new PodM(3);
}

The above still throws the same error:
Error: cannot implicitly convert expression (this) of type immutable(M) =
to  =

test.M
Error: cannot implicitly convert expression (this) of type immutable(Pod=
M)  =

to test.PodM

Compiler bug I guess...


Tomek
Dec 12 2009
parent =?iso-8859-2?B?VG9tZWsgU293afFza2k=?= <just ask.me> writes:
Dnia 13-12-2009 o 00:44:56 Tomek Sowi=F1ski <just ask.me> napisa=B3(a):


 Dnia 12-12-2009 o 13:09:49 Tomek Sowi=F1ski <just ask.me> napisa=B3(a)=


:

 But that's not all, when I mark my class immutable...

 immutable class M {
      this(byte a) { _a =3D a; }
      byte _a;
      byte a() { return _a; };
 }

 void main() {
      auto m =3D new class(4) M {
          this(byte a) { super(a); }
          override byte a() { return 3+_a; }
      };
 }

 ... the compiler says: cannot implicitly convert expression (this) of=




  =


 type immutable(M) to test.M.
 Same story for const classes. Again, compiler bug?


 It's not only about anonymous classes. Take a look at this:

 immutable class M {
      this(int a) { _a =3D a; }
      int _a;
      int a() { return _a; }
 }

 immutable class PodM : M {
      this(int a) { super(a); }
      override int a() { return 3+_a; }
 }

 void main() {
      auto m =3D new PodM(3);
 }

 The above still throws the same error:
 Error: cannot implicitly convert expression (this) of type immutable(M=


)  =


 to test.M
 Error: cannot implicitly convert expression (this) of type  =



 immutable(PodM) to test.PodM

 Compiler bug I guess...


Should've DAFS first...
http://d.puremagic.com/issues/show_bug.cgi?id=3D2610
What's disturbing is that this bug is nearly a year old... Could this be=
  =

that immutable classes lay there virtually unusable for so long?


Tomek
Dec 12 2009