digitalmars.D.learn - export classes from DLLs
- John C (39/44) May 08 2006 Anyone ever got classes to export from DLLs correctly? I've searched the...
Anyone ever got classes to export from DLLs correctly? I've searched the forum and it seems each effort has only got so far. Using a factory method in the DLL works, but that's not what I'm trying to accomplish. If I try to create an instance in a program using the DLL, the compiler complains about an undefined symbol. mydll.d implementation module mydll.di import module mydll.def Compile DLL and create import librarydmd mydll mydll.def implib /system mydll.lib mydll.dllprogram.d Compile programdmd program mydll.libThis produces the following error:program.obj Error 42: Symbol undefined __Class_7program3DogAdding __Class_7program3Dog to the EXPORTS list kills the error, but then the program throws an access violation. When I compile classes into a static library (no DLL), this problem doesn't surface.
May 08 2006
In article <e3njr2$lr0$1 digitaldaemon.com>, John C says...Anyone ever got classes to export from DLLs correctly? I've searched the forum and it seems each effort has only got so far. Using a factory method in the DLL works, but that's not what I'm trying to accomplish. If I try to create an instance in a program using the DLL, the compiler complains about an undefined symbol. mydll.d implementation module mydll.di import module mydll.def Compile DLL and create import libraryThe problem is that DLL's cannot export type information in the way you'd expect it to. In essence, each DLL compiled with D has its own type tree, completely distinct from the type tree present in your .exe file. Trace the cause of those access violations and you'll probably find they all terminate at failing implicit and explicit casts due to this. The problem goes away when you use static linking since the linker will unify all the type information, yielding totally different behavior in your code. Anyway, there are *plenty* of other gotchas with DLL's. I strongly reccomend you read the following before you get too deep into your design: http://www.prowiki.org/wiki4d/wiki.cgi?BestPractices/DLL And before you let that get you down, rest assured, I'm working hard to push DDL toward release: http://www.dsource.org/projects/ddl. - EricAnderton at yahoodmd mydll mydll.def implib /system mydll.lib mydll.dllprogram.d Compile programdmd program mydll.libThis produces the following error:program.obj Error 42: Symbol undefined __Class_7program3DogAdding __Class_7program3Dog to the EXPORTS list kills the error, but then the program throws an access violation. When I compile classes into a static library (no DLL), this problem doesn't surface.
May 08 2006
John C <johnch_atms hotmail.com> pragma wrote:In article <e3njr2$lr0$1 digitaldaemon.com>, John C says...Thanks for the explanation and the link. It's a shame it won't work - I was hoping to compile a fairly sizable class library into a DLL which other projects would link to, instead of bringing in all the code. So much for that idea! I've been keeping an eye on DDL for a while. It looks like it'll be suitable for the plug-in system I've wanted to work on. John C.Anyone ever got classes to export from DLLs correctly? I've searched the forum and it seems each effort has only got so far. Using a factory method in the DLL works, but that's not what I'm trying to accomplish. If I try to create an instance in a program using the DLL, the compiler complains about an undefined symbol. mydll.d implementation module mydll.di import module mydll.def Compile DLL and create import libraryThe problem is that DLL's cannot export type information in the way you'd expect it to. In essence, each DLL compiled with D has its own type tree, completely distinct from the type tree present in your .exe file. Trace the cause of those access violations and you'll probably find they all terminate at failing implicit and explicit casts due to this. The problem goes away when you use static linking since the linker will unify all the type information, yielding totally different behavior in your code. Anyway, there are *plenty* of other gotchas with DLL's. I strongly reccomend you read the following before you get too deep into your design: http://www.prowiki.org/wiki4d/wiki.cgi?BestPractices/DLL And before you let that get you down, rest assured, I'm working hard to push DDL toward release: http://www.dsource.org/projects/ddl. - EricAnderton at yahoodmd mydll mydll.def implib /system mydll.lib mydll.dllprogram.d Compile programdmd program mydll.libThis produces the following error:program.obj Error 42: Symbol undefined __Class_7program3DogAdding __Class_7program3Dog to the EXPORTS list kills the error, but then the program throws an access violation. When I compile classes into a static library (no DLL), this problem doesn't surface.
May 08 2006