我在我相信的某个地方做了一个错误的假设。我假设std::map只会在索引中进行比较。但是，它不是尝试比较两个uint64s，而是尝试将一个与其他东西进行比较（请参阅编译器错误）..
struct Tag { };
typedef Handle<Tag> HPowerType;
class PowerTypeMgr
{
struct PowerType { /** stuff **/ };
struct uint64_less
{
bool operator() ( const uint64& l, const uint64& r) const
{
return ((l<r)?true:false);
}
};
typedef std::map <uint64,HPowerType,uint64_less> PTHMap;
};
它会导致此编译器错误：
c:\cry_v340_3696\code\sdks\stlport\stlport\stl\debug\_tree.h(62): error C2664:
'bool PowerTypeMgr::uint64_less::operator ()(const uint64 &,const uint64 &) const' :
cannot convert parameter 2 from 'PowerTypeMgr::PowerType *const ' to 'const uint64&'
2> Reason: cannot convert from 'PowerTypeMgr::PowerType *const ' to 'const
uint64'
2> There is no context in which this conversion is possible
2> c:\cry_v340_3696\code\sdks\stlport\stlport\stl\_tree.h(570) : see
reference to function template instantiation 'bool
stlpd_std::priv::_DbgCompare<_Key,_Compare>::operator ()<_Key,_KT>(const _Kp1 &,const
_Kp2 &) const' being compiled
2> with
2> [
2> _Key=unsigned __int64,
2> _Compare=PowerTypeMgr::uint64_less,
2> _KT=PowerTypeMgr::PowerType *,
2> _Kp1=unsigned __int64,
2> _Kp2=PowerTypeMgr::PowerType *
2> ]
这是完整的用法，因为我似乎还没有发布足够的内容。注意，如果我没有通过 std::map 函子，我会得到同样的错误。我将在这里发布另一种方式。
class PowerTypeMgr
{
public:
virtual ~PowerTypeMgr();
PowerTypeMgr& Instance()
{
static PowerTypeMgr Obj;
return Obj;
}
HPowerType StorePowerType (
uint64 EMP, uint64 ESP, int wC, int chiC, int hC, const char* MPName,
const char* SPName, bool isC, bool unlock,const char* PN,const char* PC,
const char* FMT
);
void DeletePowerType(HPowerType Hpt); //not needed for powertypes,
//they should always be loaded or unloaded together
uint64 makePowerString(EMainPowers EMP, ESubPowers ESP);
bool IsComboable(HPowerType Hpt) const;
string GetPowerName(HPowerType Hpt) const;
string GetMPEffectName(HPowerType Hpt) const;
string GetSPEffectName(HPowerType Hpt) const;
string GetProjectileClass(HPowerType Hpt) const;
string GetFireModeType(HPowerType Hpt) const;
int GetHealthCost(HPowerType Hpt) const;
int GetCHICost(HPowerType Hpt) const;
int GetWeaponCost(HPowerType Hpt) const;
bool IsUnlocked(HPowerType Hpt) const;
uint64 GetPowerString(HPowerType Hpt) const;
// Only things that may change during the course of game execution //
void StorePowerName(HPowerType Hpt, string pn);
void Unlock(HPowerType Hpt);//, bool L); //true = unlock it
void Lock(HPowerType Hpt);
bool SaveGame(/* GamePak, SaveName*/) {}//TODO
bool LoadGame(/* GamePak, SaveName*/) {}//TODO
private:
struct PowerType
{
uint64 thePower; //64-bit string where uppermost 8 bits is the EMainPower, and lower 56 is ESubPower
EMainPowers mainPower; //currently unused
ESubPowers subPower; //ditto
bool isComboable;
bool isUnlocked;
int weaponCost; //weapon cost (to hold)
int CHIcost; //cost to CHI meter to use it.
int healthCost; //additional healthCost to use it
string powerName;
string MPEffectName;
string SPEffectName;
string projectileClass;
string fireModeType;
//MEMBERS --------------------------------------------------<<<
void Unload();
EMainPowers getMainPower() const;
EMainPowers convertToMainPower(const uint64& bitstring);
ESubPowers getSubPower() const;
ESubPowers convertToSubPower(const uint64& bitstring);
}; //end struct PowerType
//--------------------------------------------------------------------------------------------------------
PowerTypeMgr(); //SINGLETON pattern
typedef std::pair<uint64,HPowerType> PowerMap_Pair;
typedef std::map <uint64,HPowerType> PTHMap;//,int64_less> PTHMap; //,uint64_less> PTHMap; //O(logn) look up bitstr
PTHMap m_PTHMap; //...
typedef std::pair<PTHMap::iterator,bool> indexInsertRC;
typedef HandleMgr <PowerType, HPowerType> PowerHandle;
PowerHandle m_PowerTypeHMgr;
bool inited; //Used in assert & checking if trying to load more than once
int totalPowerTypes;
}; //end PowerTypeMgr
这是编译器错误（VC Express 2010）
'2> PowerTypeMgr.cpp
2>c:\cry_v340_3696\code\sdks\stlport\stlport\stl\debug\_tree.h(62): error C2664: 'bool stlpd_std::less<_Tp>::operator ()(const _Tp &,const _Tp &) const' : cannot convert parameter 2 from 'PowerTypeMgr::PowerType *const ' to 'const uint64 &'
2> with
2> [
2> _Tp=uint64
2> ]
2> Reason: cannot convert from 'PowerTypeMgr::PowerType *const ' to 'const uint64'
2> There is no context in which this conversion is possible
2> c:\cry_v340_3696\code\sdks\stlport\stlport\stl\_tree.h(570) : see reference to function template instantiation 'bool stlpd_std::priv::_DbgCompare<_Key,_Compare>::operator ()<_Key,_KT>(const _Kp1 &,const _Kp2 &) const' being compiled
2> with
2> [
2> _Key=unsigned __int64,
2> _Compare=stlpd_std::less<uint64>,
2> _KT=PowerTypeMgr::PowerType *,
2> _Kp1=unsigned __int64,
2> _Kp2=PowerTypeMgr::PowerType *
2> ]
2> c:\cry_v340_3696\code\sdks\stlport\stlport\stl\_tree.h(560) : see reference to function template instantiation 'stlpd_std::priv::_NonDbg_Rb_tree<_Key,_Compare,_Value,_KeyOfValue,_Traits,_Alloc>::_Base_ptr stlpd_std::priv::_NonDbg_Rb_tree<_Key,_Compare,_Value,_KeyOfValue,_Traits,_Alloc>::_M_find<_KT>(const _KT &) const' being compiled
2> with
2> [
2> _Key=unsigned __int64,
2> _Compare=stlpd_std::priv::_DbgCompare<unsigned __int64,stlpd_std::less<uint64>>,
2> _Value=stlpd_std::pair<const uint64,HPowerType>,
2> _KeyOfValue=stlpd_std::priv::_Select1st<stlpd_std::pair<const uint64,HPowerType>>,
2> _Traits=stlpd_std::priv::_MapTraitsT<stlpd_std::pair<const uint64,HPowerType>>,
2> _Alloc=stlpd_std::allocator<stlpd_std::pair<const uint64,HPowerType>>,
2> _KT=PowerTypeMgr::PowerType *
2> ]
2> c:\cry_v340_3696\code\sdks\stlport\stlport\stl\debug\_tree.h(178) : see
reference to function template instantiation 'stlpd_std::priv::_Rb_tree_iterator<_Value,_Traits> stlpd_std::priv::_NonDbg_Rb_tree<_Key,_Compare,_Value,_KeyOfValue,_Traits,_Alloc>::find<_KT>(const _KT &)' being compiled
2> with
2> [
2> _Value=stlpd_std::pair<const uint64,HPowerType>,
2> _Traits=stlpd_std::priv::_MapTraitsT<stlpd_std::pair<const uint64,HPowerType>>,
2> _Key=unsigned __int64,
2> _Compare=stlpd_std::priv::_DbgCompare<unsigned __int64,stlpd_std::less<uint64>>,
2> _KeyOfValue=stlpd_std::priv::_Select1st<stlpd_std::pair<const uint64,HPowerType>>,
2> _Alloc=stlpd_std::allocator<stlpd_std::pair<const uint64,HPowerType>>,
2> _KT=PowerTypeMgr::PowerType *
2> ]
2> c:\cry_v340_3696\code\sdks\stlport\stlport\stl\_map.h(214) : see reference to function template instantiation 'stlpd_std::priv::_DBG_iter<_Container,_Traits> stlpd_std::priv::_Rb_tree<_Key,_Compare,_Value,_KeyOfValue,stlpd_std::priv::_MapTraitsT<_Tp>,_Alloc>::find<_KT>(const _KT &)' being compiled
2> with
2> [
2> _Container=stlpd_std::priv::_NonDbg_Rb_tree<unsigned __int64,stlpd_std::priv::_DbgCompare<unsigned __int64,stlpd_std::less<uint64>>,stlpd_std::pair<const uint64,HPowerType>,stlpd_std::priv::_Select1st<stlpd_std::pair<const uint64,HPowerType>>,stlpd_std::priv::_MapTraitsT<stlpd_std::pair<const uint64,HPowerType>>,stlpd_std::allocator<stlpd_std::pair<const uint64,HPowerType>>>,
2> _Traits=stlpd_std::priv::_DbgTraits<stlpd_std::priv::_MapTraitsT<stlpd_std::pair<const uint64,HPowerType>>>,
2> _Key=unsigned __int64,
2> _Compare=stlpd_std::less<uint64>,
2> _Value=stlpd_std::pair<const uint64,HPowerType>,
2> _KeyOfValue=stlpd_std::priv::_Select1st<stlpd_std::pair<const uint64,HPowerType>>,
2> _Tp=stlpd_std::pair<const uint64,HPowerType>,
2> _Alloc=stlpd_std::allocator<stlpd_std::pair<const uint64,HPowerType>>,
2> _KT=PowerTypeMgr::PowerType *
2> ]
2> c:\cry_v340_3696\code\game\gamedll\monk\powertypemgr.cpp(78) : see reference to function template instantiation 'stlpd_std::priv::_DBG_iter<_Container,_Traits> stlpd_std::map<_Key,_Tp>::find<PowerTypeMgr::PowerType*>(const _KT &)' being compiled
2> with
2> [
2> _Container=stlpd_std::priv::_NonDbg_Rb_tree<unsigned __int64,stlpd_std::priv::_DbgCompare<unsigned __int64,stlpd_std::less<uint64>>,stlpd_std::pair<const uint64,HPowerType>,stlpd_std::priv::_Select1st<stlpd_std::pair<const uint64,HPowerType>>,stlpd_std::priv::_MapTraitsT<stlpd_std::pair<const uint64,HPowerType>>,stlpd_std::allocator<stlpd_std::pair<const uint64,HPowerType>>>,
2> _Traits=stlpd_std::priv::_DbgTraits<stlpd_std::priv::_MapTraitsT<stlpd_std::pair<const uint64,HPowerType>>>,
2> _Key=uint64,
2> _Tp=HPowerType,
2> _KT=PowerTypeMgr::PowerType *
2> ]
2>c:\cry_v340_3696\code\sdks\stlport\stlport\stl\debug\_tree.h(62): error C2664: 'bool stlpd_std::less<_Tp>::operator ()(const _Tp &,const _Tp &) const' : cannot convert parameter 1 from 'PowerTypeMgr::PowerType *const ' to 'const uint64 &'
2> with
2> [
2> _Tp=uint64
2> ]
2> Reason: cannot convert from 'PowerTypeMgr::PowerType *const ' to 'const uint64'
2> There is no context in which this conversion is possible
2> c:\cry_v340_3696\code\sdks\stlport\stlport\stl\_tree.h(576) : see reference to function template instantiation 'bool stlpd_std::priv::_DbgCompare<_Key,_Compare>::operator ()<_KT,_Key>(const _Kp1 &,const _Kp2 &) const' being compiled
2> with
2> [
2> _Key=unsigned __int64,
2> _Compare=stlpd_std::less<uint64>,
2> _KT=PowerTypeMgr::PowerType *,
2> _Kp1=PowerTypeMgr::PowerType *,
2> _Kp2=unsigned __int64
2> ]
2> PowerWeapon.cpp
...'