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c++ - fatal bug: cannot link static singleton class

reply "Luna Kid" <lunakid neuropolis.org> writes:
This fails to link (dmc m1.cpp m2.cpp):

m1.cpp:

    #include "single.h"
    int main() { X::instance(); }

m2.cpp:

    #include "single.h"
    void f() { X::instance(); }

single.h

    struct X {
         static void instance() { static X x; }
         X() {} // comment out the ctor to link successfully
    };


The error is:

link m1+m2,,,user32+kernel32/noi;
OPTLINK (R) for Win32  Release 7.50B1
Copyright (C) Digital Mars 1989 - 2001  All Rights Reserved

m2.obj(m2)  Offset 0011AH Record Type 0091
 Error 1: Previous Definition Different : ?x ?1??instance X  SAXXZ (void cdecl
X::?1??inst
ance::x(void ))

--- errorlevel 1


Thanks,
Sz.
Nov 04 2003
parent reply "Luna Kid" <lunakid neuropolis.org> writes:
This one may be sort of important.

I hope I'm wrong, but I found the static singleton idiom
as the only solution for some cases (like a header-only
implementation of a debug output controller, or default
allocator instances), and I had to temporarily drop DMC
support for our lib due to the problem below.

Any ideas for workaround? Can I still use some kind of
a "persistent" class instance (living while the process
lives; i.e. some static) without adding a .cpp and losing
portability?

Cheers,
Sz.


"Luna Kid" <lunakid neuropolis.org> wrote in message
news:bo9lvq$mj9$1 digitaldaemon.com...
 This fails to link (dmc m1.cpp m2.cpp):

 m1.cpp:

     #include "single.h"
     int main() { X::instance(); }

 m2.cpp:

     #include "single.h"
     void f() { X::instance(); }

 single.h

     struct X {
          static void instance() { static X x; }
          X() {} // comment out the ctor to link successfully
     };


 The error is:

 link m1+m2,,,user32+kernel32/noi;
 OPTLINK (R) for Win32  Release 7.50B1
 Copyright (C) Digital Mars 1989 - 2001  All Rights Reserved

 m2.obj(m2)  Offset 0011AH Record Type 0091
  Error 1: Previous Definition Different : ?x ?1??instance X  SAXXZ (void cdecl
X::?1??inst
 ance::x(void ))

 --- errorlevel 1


 Thanks,
 Sz.

Nov 07 2003
parent reply "Walter" <walter digitalmars.com> writes:
Have you tried the latest beta DMC++?

"Luna Kid" <lunakid neuropolis.org> wrote in message
news:bog3ar$11jv$1 digitaldaemon.com...
 This one may be sort of important.

 I hope I'm wrong, but I found the static singleton idiom
 as the only solution for some cases (like a header-only
 implementation of a debug output controller, or default
 allocator instances), and I had to temporarily drop DMC
 support for our lib due to the problem below.

 Any ideas for workaround? Can I still use some kind of
 a "persistent" class instance (living while the process
 lives; i.e. some static) without adding a .cpp and losing
 portability?

 Cheers,
 Sz.


 "Luna Kid" <lunakid neuropolis.org> wrote in message

 This fails to link (dmc m1.cpp m2.cpp):

 m1.cpp:

     #include "single.h"
     int main() { X::instance(); }

 m2.cpp:

     #include "single.h"
     void f() { X::instance(); }

 single.h

     struct X {
          static void instance() { static X x; }
          X() {} // comment out the ctor to link successfully
     };


 The error is:

 link m1+m2,,,user32+kernel32/noi;
 OPTLINK (R) for Win32  Release 7.50B1
 Copyright (C) Digital Mars 1989 - 2001  All Rights Reserved

 m2.obj(m2)  Offset 0011AH Record Type 0091
  Error 1: Previous Definition Different : ?x ?1??instance X  SAXXZ (void


 ance::x(void ))

 --- errorlevel 1


 Thanks,
 Sz.


Nov 07 2003
parent "Luna Kid" <lunakid neuropolis.org> writes:
Yes (after you suggested...). Same thing.

Thanks,
Sz.

"Walter" <walter digitalmars.com> wrote in message
news:bogmhh$1sf7$1 digitaldaemon.com...
 Have you tried the latest beta DMC++?

 "Luna Kid" <lunakid neuropolis.org> wrote in message
 news:bog3ar$11jv$1 digitaldaemon.com...
 This one may be sort of important.

 I hope I'm wrong, but I found the static singleton idiom
 as the only solution for some cases (like a header-only
 implementation of a debug output controller, or default
 allocator instances), and I had to temporarily drop DMC
 support for our lib due to the problem below.

 Any ideas for workaround? Can I still use some kind of
 a "persistent" class instance (living while the process
 lives; i.e. some static) without adding a .cpp and losing
 portability?

 Cheers,
 Sz.


 "Luna Kid" <lunakid neuropolis.org> wrote in message

 This fails to link (dmc m1.cpp m2.cpp):

 m1.cpp:

     #include "single.h"
     int main() { X::instance(); }

 m2.cpp:

     #include "single.h"
     void f() { X::instance(); }

 single.h

     struct X {
          static void instance() { static X x; }
          X() {} // comment out the ctor to link successfully
     };


 The error is:

 link m1+m2,,,user32+kernel32/noi;
 OPTLINK (R) for Win32  Release 7.50B1
 Copyright (C) Digital Mars 1989 - 2001  All Rights Reserved

 m2.obj(m2)  Offset 0011AH Record Type 0091
  Error 1: Previous Definition Different : ?x ?1??instance X  SAXXZ (void


 ance::x(void ))

 --- errorlevel 1


 Thanks,
 Sz.



Nov 07 2003