Topic: std::unique_ptr for DB objects... or bad idea

[It's Alive!]

std::unique_ptr for DB objects... or bad idea lol

Code - C++: [Select]

1. template <class T>
2. class DBObjectDeleter
3. {
4. public:
5.     inline void operator()(T *p)
6.     {
7.         if (p != nullptr)
8.             return this->close(p);
9.     }
10. private:
11.     inline void close(T *p)
12.     {
13.         if (!p->objectId().isNull())
14.             p->close();
15.         else
16.             this->deleter(p);
17.     }
18.     inline void deleter(T *p)
19.     {
20.         delete p;
21.         p = nullptr;
22.     }
23. };
24.  
25. template<typename T>
26. using unique_dbo_ptr = std::unique_ptr<T, DBObjectDeleter<T>>;
27.  
28. typedef unique_dbo_ptr<AcDbLine> AcDbLineUPtr;
29.  

Code - C++: [Select]

1.     void quaz()
2.     {
3.         AcDbLineUPtr pLine(new AcDbLine());
4.         //...
5.     }
6.  

[It's Alive!]

along the same lines

Code - C++: [Select]

1. typedef std::unique_ptr<AcDbDictionaryIterator> AcDbDictionaryIteratorPtr;
2. typedef std::unique_ptr<AcDbBlockTableIterator> AcDbBlockTableIteratorPtr;
3. typedef std::unique_ptr<AcDbBlockTableRecordIterator> AcDbBlockTableRecordIteratorPtr;
4.  
5. inline AcDbBlockTableIteratorPtr createBlockTableIterator
6. (
7.     const AcDbBlockTable* pSrc,
8.     Acad::ErrorStatus *stat = nullptr,
9.     bool atBeginning = true,
10.     bool skipDeleted = true
11. )
12. {
13.     Acad::ErrorStatus _stat = eOk;
14.     AcDbBlockTableIterator *pIter = nullptr;
15.     if (pSrc != nullptr)
16.         _stat = pSrc->newIterator(pIter, atBeginning, skipDeleted);
17.     if (stat != nullptr)
18.         *stat = _stat;
19.     return AcDbBlockTableIteratorPtr(pIter);
20. }
21.  
22. inline AcDbBlockTableRecordIteratorPtr createBlockTableRecordIterator
23. (
24.     const AcDbBlockTableRecord* pSrc,
25.     Acad::ErrorStatus *stat = nullptr,
26.     bool atBeginning = true,
27.     bool skipDeleted = true
28. )
29. {
30.     Acad::ErrorStatus _stat = eOk;
31.     AcDbBlockTableRecordIterator *pIter = nullptr;
32.     if (pSrc != nullptr)
33.         _stat = pSrc->newIterator(pIter, atBeginning, skipDeleted);
34.     if (stat != nullptr)
35.         *stat = _stat;
36.     return AcDbBlockTableRecordIteratorPtr(pIter);
37. }
38.  

Code - C++: [Select]

1.    static void foo(void)
2.     {
3.         AcDbObjectId rid, id;
4.         AcDbDatabase *pDb = acdbHostApplicationServices()->workingDatabase();
5.         AcDbBlockTablePointer pBT(pDb->blockTableId());
6.         AcDbBlockTableIteratorPtr pBTIter = createBlockTableIterator(pBT);
7.         for (pBTIter->start(); !pBTIter->done(); pBTIter->step())
8.         {
9.             if (pBTIter->getRecordId(rid) == eOk)
10.             {
11.                 AcDbBlockTableRecordPointer record(rid);
12.                 AcDbBlockTableRecordIteratorPtr piter = createBlockTableRecordIterator(record);
13.                 for (piter->start(); !piter->done(); piter->step())
14.                 {
15.                     if (piter->getEntityId(id) == eOk)
16.                     {
17.                         AcDbEntityPointer pEnt(id);
18.                         //... yada yada
19.                     }
20.                 }
21.             }
22.         }
23.     }
24.  

[MickD]

Still brushing up on my C++ but when I first read about the new smart pointers this was the first place I thought about using them (i.e. in some ObjectARX).

I guess it depends on the size of your function and how many 'new' pointers you have to manage, then again they would be used quite a bit in many functions so I think yes, good idea

[It's Alive!]

I’ve been using AcDbObjectPointer for dbobjects and std::unique_ptr for iterators (and everything else)

Code - C++: [Select]

1. //
2. template<typename IteratorType>
3. constexpr auto makeIterator = [](const auto& record)
4. {
5.     IteratorType *pIter = nullptr;
6.     Acad::ErrorStatus es = record.newIterator(pIter);
7.     return std::make_tuple(es, std::unique_ptr<IteratorType>(pIter));
8. };
9. constexpr auto makeBlockTableIterator = makeIterator<AcDbBlockTableIterator>;
10. constexpr auto makeBlockTableRecordIterator = makeIterator<AcDbBlockTableRecordIterator>;
11.  
12.  
13. //
14.    if (AcDbBlockTablePointer pBt(blockTableId, AcDb::kForRead); pBt.openStatus() == eOk)
15.     {
16.         if (auto[es, btTter] = makeBlockTableIterator(*pBt); es == eOk)
17.         {
18.             for (btTter->start(); !btTter->done(); btTter->step())
19.             {
20.                ...
21.             }
22.         }
23.     }
24.  

and I have been passing by refrence

Code - C++: [Select]

1.  
2.     void woohoo(AcDbObjectId id)
3.     {
4.         if (AcDbObjectPointer<AcDbLine> pLine(id); pLine.openStatus() == eOk)
5.         {
6.             yahoo(*pLine);
7.         }
8.     }
9.  
10.     Acad::ErrorStatus yahoo(AcDbLine& line)
11.     {
12.         AcString layer;
13.         return line.layer(layer);
14.     }
15.  

[It's Alive!]

of course this may change in a few weeks 

[MickD]

toight