unique_ptr参数误差C2664

Question

我最近刚刚听说了新的unique_ptr in C++11，并想试一试。

我更改了这个代码：

void CreateDummySpell(uint32 id)
{
    const char * name = "Dummy Trigger";
    SpellEntry * sp = new SpellEntry;
    memset(sp, 0, sizeof(SpellEntry));
    sp->Id = id;
    sp->Attributes = 384;
    sp->AttributesEx = 268435456;
    sp->AttributesExB = 4;
    sp->CastingTimeIndex=1;
    sp->procChance=75;
    sp->rangeIndex=13;
    sp->EquippedItemClass=uint32(-1);
    sp->Effect[0]=3;
    sp->EffectImplicitTargetA[0]=25;
    sp->NameHash=crc32((const unsigned char*)name, (unsigned int)strlen(name));
    sp->dmg_multiplier[0]=1.0f;
    sp->StanceBarOrder=-1;
    dbcSpell.SetRow(id,sp);
    sWorld.dummyspells.push_back(sp);
}

到这个

void CreateDummySpell(uint32 id)
{
    const char * name = "Dummy Trigger";
//  SpellEntry * sp = new SpellEntry;
    std::unique_ptr<SpellEntry> sp(new SpellEntry);
    memset(sp, 0, sizeof(SpellEntry));
    sp->Id = id;
    sp->Attributes = 384;
    sp->AttributesEx = 268435456;
    sp->AttributesExB = 4;
    sp->CastingTimeIndex=1;
    sp->procChance=75;
    sp->rangeIndex=13;
    sp->EquippedItemClass=uint32(-1);
    sp->Effect[0]=3;
    sp->EffectImplicitTargetA[0]=25;
    sp->NameHash=crc32((const unsigned char*)name, (unsigned int)strlen(name));
    sp->dmg_multiplier[0]=1.0f;
    sp->StanceBarOrder=-1;
    dbcSpell.SetRow(id,sp);
    sWorld.dummyspells.push_back(sp);
}

现在我得到了这个错误：

error C2664: 'void *memset(void *,int,size_t)': cannot convert argument 1 from 'std::unique_ptr<SpellEntry,std::default_delete<_Ty>>' to 'void *'
2>          with
2>          [
2>              _Ty=SpellEntry
2>          ]
2>  ..\..\src\arcemu-world\SpellFixes.cpp(29): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
2>..\..\src\arcemu-world\SpellFixes.cpp(43): error C2664: 'void DBCStorage<SpellEntry>::SetRow(uint32,T *)': cannot convert argument 2 from 'std::unique_ptr<SpellEntry,std::default_delete<_Ty>>' to 'SpellEntry *'
2>          with
2>          [
2>              T=SpellEntry
2>          ]
2>          and
2>          [
2>              _Ty=SpellEntry
2>          ]
2>  ..\..\src\arcemu-world\SpellFixes.cpp(43): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
2>..\..\src\arcemu-world\SpellFixes.cpp(44): error C2664: 'void std::list<SpellEntry *,std::allocator<_Kty>>::push_back(const _Ty &)': cannot convert argument 1 from 'std::unique_ptr<SpellEntry,std::default_delete<_Ty>>' to 'SpellEntry *&&'
2>          with
2>          [
2>              _Kty=SpellEntry *
2>  ,            _Ty=SpellEntry *
2>          ]
2>          and
2>          [
2>              _Ty=SpellEntry
2>          ]
2>  ..\..\src\arcemu-world\SpellFixes.cpp(44): note: Reason: cannot convert from 'std::unique_ptr<SpellEntry,std::default_delete<_Ty>>' to 'SpellEntry *'
2>          with
2>          [
2>              _Ty=SpellEntry
2>          ]
2>  ..\..\src\arcemu-world\SpellFixes.cpp(44): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

看来我可以把sp作为参数传递。如何使用unique_ptr智能指针传递sp作为参数？

提前谢谢。

短信太短了..。

Answer 1

您可能应该重新考虑使用memset (只需值-初始化它，例如new SomeClass() )，但是在一般情况下，如果您想传递unique_ptr的内部指针(例如指向遗留函数)，则使用它的get函数。