The code below won't compile, it gives me an unresolved external. Anyone know why?
Code:class BaseParticleManager { public: virtual ~BaseParticleManager( void ); template<typename T> void AddNewParticle(const T & throwaway); private: std::list < Particle * > ParticleList; };Code:template<typename T> void BaseParticleManager :: AddNewParticle(const T & throwaway) { ParticleList.push_back( new T ); }
What compiler are you using? Do you have the destructor defined anywhere? The template stuff looks fine.
"...the results are undefined, and we all know what "undefined" means: it means it works during development, it works during testing, and it blows up in your most important customers' faces." --Scott Meyers
>it gives me an unresolved external
Could you give us the text of that error? My error with your very incomplete code was talking about BaseParticleManager's destructor. After giving it a body, the compile and link only gave one warning. To clear the warning, you can remove the argument to AddNewParticle and give the template an explicit instantiation:
Code:template<typename T> void BaseParticleManager :: AddNewParticle() { ParticleList.push_back( new T ); } ... BaseParticleManager bpm; bpm.AddNewParticle<Particle>();
My best code is written with the delete key.
class SnowParticle : Public Particle;
thought I'd add that.
and when I do it explicitly, like you said...TestTask.obj : error LNK2019: unresolved external symbol "public: void __thiscall BaseParticleManager::AddNewParticle<class SnowParticle>(class SnowParticle const &)" (??$AddNewParticle@VSnowParticle@@@BaseParticleMan ager@@QAEXABVSnowParticle@@@Z) referenced in function "public: virtual bool __thiscall CTestTask::Start(void)" (?Start@CTestTask@@UAE_NXZ)
Debug/RTMB.exe : fatal error LNK1120: 1 unresolved externals
TestTask.obj : error LNK2019: unresolved external symbol "public: void __thiscall BaseParticleManager::AddNewParticle<class SnowParticle>(void)" (??$AddNewParticle@VSnowParticle@@@BaseParticleMan ager@@QAEXXZ) referenced in function "public: virtual bool __thiscall CTestTask::Start(void)" (?Start@CTestTask@@UAE_NXZ)
Last edited by Trauts; 03-12-2004 at 09:36 PM.
Post a short program that we can compile that exhibits the problem.
My best code is written with the delete key.
it works when I recompile it elsewhere, in a separate program... thats REALLY weird.
>Attachment: particles.zip
...
>it works when I recompile it elsewhere, in a separate program...
Clearly you're making the mistake in your big program but not in the little program. Compare and contrast the relevant parts of the two programs. I can't help you because I don't download attached zip files, like many other regular contributors to cprogramming.
My best code is written with the delete key.
do you want me to attach them as .cpp/.h's?
I DID copy and paste, but I also deleted some excess stuff... hrm..
It works fine, doesn't give me the unresolved external, unless I uncomment this line:
ParticleController.AddNewParticle<SnowParticle>();
got it working. it wasn't recognizing it in the .cpp for some reason
