Sorry, the solution I presented here is absolutely incorrect. Here is the corrected version. I've tested. //______________SOLUTION_CODE_______________ template<class T> class condition_selector : public std::unary_function<bool, T> { T true_, false_; public: condition_selector(T true__, T false__) : true_(true__), false_(false__) {} T operator()(bool condition) { return condition? true_ : false_; } }; // helper function template<class T> condition_selector<T> make_condition_selector(T true_, T false_) { return condition_selector<T>(true_, false_); } // if(CONDITION), I'll take care of deleting the ptr, or let it be otherwise #define DECLARE_PTR_AUTO_DELETOR_CONDITIONAL(CLASS, VAR_PTR, CONDITION)\ boost::scoped_ptr<CLASS> auto__deletor__for__ ## VAR_PTR (\ make_condition_selector(VAR_PTR, static_cast<CLASS*>(0))(CONDITION)) // I don;t know why this version, using lambda, does not work //#define DECLARE_PTR_AUTO_DELETOR_CONDITIONAL(CLASS, VAR_PTR, CONDITION)\ // boost::scoped_ptr<CLASS> auto__deletor__for__ ## VAR_PTR (\ // boost::lambda::ret<CLASS*>(boost::lambda::if_then_else(_1,\ // VAR_PTR, static_cast<CLASS*>(0)))(static_cast<bool>(CONDITION))) //____________APPLICATION____________ AcDbCircle *pFace =new AcDbCircle (AcGePoint3d::kOrigin, AcGeVector3d::kZAxis, 1.0) ; AcDbCircle *pLeftEye =new AcDbCircle (AcGePoint3d (0.33, 0.25, 0.0), AcGeVector3d::kZAxis, 0.1) ; AcDbCircle *pRightEye =new AcDbCircle (AcGePoint3d (-0.33, 0.25, 0.0), AcGeVector3d::kZAxis, 0.1) ; AcDbArc *pMouth =new AcDbArc (AcGePoint3d (0, 0.5, 0), 1.0, 3.141592 + (3.141592 * 0.3), 3.141592 + (3.141592 * 0.7)) ; // Set the color property. pFace->setColorIndex (2) ; pLeftEye->setColorIndex (5) ; pRightEye->setColorIndex (5) ; pMouth->setColorIndex (1) ; // add the entities to the new block table record es = pBlockTableRecord->appendAcDbEntity (pFace) DECLARE_PTR_AUTO_DELETOR(AcDbCircle, pFace, (es!=Acad::eOk)); if ( es != Acad::eOk ) { //delete pFace ; // all these 'delete ...' not needed any more ... //delete pLeftEye ; //delete pRightEye ; //delete pMouth ; pBlockTableRecord->erase () ; pBlockTableRecord->close () ; return (es) ; } pFace->close () ; // ... ... Sorry for the noise. B/Rgds Max ================================================================================ There seems to be a solution that can make the code a little bit cleaner and easier to maintain. #define DECLARE_PTR_AUTO_DELETOR(CLASS, VAR_PTR)\ boost::scoped_ptr auto__deletor__for__ ## VAR_PTR (VAR_PTR) AcDbCircle *pFace =new AcDbCircle (AcGePoint3d::kOrigin, AcGeVector3d::kZAxis, 1.0) ; AcDbCircle *pLeftEye =new AcDbCircle (AcGePoint3d (0.33, 0.25, 0.0), AcGeVector3d::kZAxis, 0.1) ; AcDbCircle *pRightEye =new AcDbCircle (AcGePoint3d (-0.33, 0.25, 0.0), AcGeVector3d::kZAxis, 0.1) ; AcDbArc *pMouth =new AcDbArc (AcGePoint3d (0, 0.5, 0), 1.0, 3.141592 + (3.141592 * 0.3), 3.141592 + (3.141592 * 0.7)) ; DECLARE_PTR_AUTO_DELETOR(AcDbCircle, pFace); DECLARE_PTR_AUTO_DELETOR(AcDbCirclep, LeftEye); DECLARE_PTR_AUTO_DELETOR(AcDbCircle, pRightEye); DECLARE_PTR_AUTO_DELETOR(AcDbArc, pMouth); // Set the color property. pFace->setColorIndex (2) ; pLeftEye->setColorIndex (5) ; pRightEye->setColorIndex (5) ; pMouth->setColorIndex (1) ; // add the entities to the new block table record if ( (es =pBlockTableRecord->appendAcDbEntity (pFace)) != Acad::eOk ) { //delete pFace ; // all these 'delete ...' not needed any more ... //delete pLeftEye ; //delete pRightEye ; //delete pMouth ; pBlockTableRecord->erase () ; pBlockTableRecord->close () ; return (es) ; } pFace->close () ; if ( (es =pBlockTableRecord->appendAcDbEntity (pLeftEye)) != Acad::eOk ) { //delete pLeftEye ; //delete pRightEye ; //delete pMouth ; pBlockTableRecord->erase () ; pBlockTableRecord->close () ; return (es) ; } pLeftEye->close () ; if ( (es =pBlockTableRecord->appendAcDbEntity (pRightEye)) != Acad::eOk ) { //delete pRightEye ; //delete pMouth ; pBlockTableRecord->erase () ; pBlockTableRecord->close () ; return (es) ; } pRightEye->close () ; if ( (es =pBlockTableRecord->appendAcDbEntity (pMouth)) != Acad::eOk ) { //delete pMouth ; pBlockTableRecord->erase () ; pBlockTableRecord->close () ; return (es) ; } pMouth->close () ; Thanks you all that hepled. B/Rgds Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )