Discussion :

[loustak]

Bonjour,
J'ai un problème que je ne comprends pas, j'ai une map créer ici :

Code :

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static std::map<std::string, T*>* _list;

puis déclarer hors de la classe comme ceci :

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template <typename T> std::map<std::string, T*>* ConstructableJsonHolder<T>::_list = NULL;

et enfin pour éviter le problème d'initialisation des variables static j'ai une méthode qui retourne un pointeur vers la map :

Code :

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static std::map<std::string, T*>* list() {
	if (_list == NULL) {
		_list = new std::map<std::string, T*>();
	}
	return _list;
}

Jusque là aucun soucis.

Le problème est que étant donné que ma map contient des objets créer avec new il faut que je les delete, donc lors de la destruction de ma classe j'essaye de libérer la mémoire en bouclant sur la map avec ce code :

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virtual ~ConstructableJsonHolder() {
	for (auto obj : list()) {
               // instruction
	}
}

le problème est que celà créer des erreurs de compilation que je ne comprends pas :

src/../inc/ConstructableJson.hpp: In instantiation of ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’:
src/Tile.cpp:4:12: required from here
src/../inc/ConstructableJson.hpp:23:3: error: no matching function for call to ‘begin(std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*&)’
for (auto obj : list()) {
^
In file included from /usr/include/c++/5/string:51:0,
from /usr/include/c++/5/bits/locale_classes.h:40,
from /usr/include/c++/5/bits/ios_base.h:41,
from /usr/include/c++/5/ios:42,
from /usr/include/c++/5/ostream:38,
from /usr/include/c++/5/iostream:39,
from src/../inc/Tile.hpp:4,
from src/Tile.cpp:1:
/usr/include/c++/5/bits/range_access.h:87:5: note: candidate: template<class _Tp, long unsigned int _Nm> _Tp* std::begin(_Tp (&)[_Nm])
begin(_Tp (&__arr)[_Nm])
^
/usr/include/c++/5/bits/range_access.h:87:5: note: template argument deduction/substitution failed:
In file included from src/../inc/Tile.hpp:8:0,
from src/Tile.cpp:1:
src/../inc/ConstructableJson.hpp:23:3: note: mismatched types ‘_Tp [_Nm]’ and ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*’
for (auto obj : list()) {
^
In file included from /usr/include/c++/5/string:51:0,
from /usr/include/c++/5/bits/locale_classes.h:40,
from /usr/include/c++/5/bits/ios_base.h:41,
from /usr/include/c++/5/ios:42,
from /usr/include/c++/5/ostream:38,
from /usr/include/c++/5/iostream:39,
from src/../inc/Tile.hpp:4,
from src/Tile.cpp:1:
/usr/include/c++/5/bits/range_access.h:58:5: note: candidate: template<class _Container> decltype (__cont.begin()) std::begin(const _Container&)
begin(const _Container& __cont) -> decltype(__cont.begin())
^
/usr/include/c++/5/bits/range_access.h:58:5: note: template argument deduction/substitution failed:
/usr/include/c++/5/bits/range_access.h: In substitution of ‘template<class _Container> decltype (__cont.begin()) std::begin(const _Container&) [with _Container = std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*]’:
src/../inc/ConstructableJson.hpp:23:3: required from ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/bits/range_access.h:58:5: error: request for member ‘begin’ in ‘__cont’, which is of pointer type ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >* const’ (maybe you meant to use ‘->’ ?)
src/../inc/ConstructableJson.hpp: In instantiation of ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’:
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/bits/range_access.h:48:5: note: candidate: template<class _Container> decltype (__cont.begin()) std::begin(_Container&)
begin(_Container& __cont) -> decltype(__cont.begin())
^
/usr/include/c++/5/bits/range_access.h:48:5: note: template argument deduction/substitution failed:
/usr/include/c++/5/bits/range_access.h: In substitution of ‘template<class _Container> decltype (__cont.begin()) std::begin(_Container&) [with _Container = std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*]’:
src/../inc/ConstructableJson.hpp:23:3: required from ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/bits/range_access.h:48:5: error: request for member ‘begin’ in ‘__cont’, which is of pointer type ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*’ (maybe you meant to use ‘->’ ?)
In file included from /usr/include/c++/5/bits/range_access.h:36:0,
from /usr/include/c++/5/string:51,
from /usr/include/c++/5/bits/locale_classes.h:40,
from /usr/include/c++/5/bits/ios_base.h:41,
from /usr/include/c++/5/ios:42,
from /usr/include/c++/5/ostream:38,
from /usr/include/c++/5/iostream:39,
from src/../inc/Tile.hpp:4,
from src/Tile.cpp:1:
src/../inc/ConstructableJson.hpp: In instantiation of ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’:
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/initializer_list:89:5: note: candidate: template<class _Tp> constexpr const _Tp* std::begin(std::initializer_list<_Tp>)
begin(initializer_list<_Tp> __ils) noexcept
^
/usr/include/c++/5/initializer_list:89:5: note: template argument deduction/substitution failed:
In file included from src/../inc/Tile.hpp:8:0,
from src/Tile.cpp:1:
src/../inc/ConstructableJson.hpp:23:3: note: mismatched types ‘std::initializer_list<_Tp>’ and ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*’
for (auto obj : list()) {
^
src/../inc/ConstructableJson.hpp:23:3: error: no matching function for call to ‘end(std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*&)’
In file included from /usr/include/c++/5/string:51:0,
from /usr/include/c++/5/bits/locale_classes.h:40,
from /usr/include/c++/5/bits/ios_base.h:41,
from /usr/include/c++/5/ios:42,
from /usr/include/c++/5/ostream:38,
from /usr/include/c++/5/iostream:39,
from src/../inc/Tile.hpp:4,
from src/Tile.cpp:1:
/usr/include/c++/5/bits/range_access.h:97:5: note: candidate: template<class _Tp, long unsigned int _Nm> _Tp* std::end(_Tp (&)[_Nm])
end(_Tp (&__arr)[_Nm])
^
/usr/include/c++/5/bits/range_access.h:97:5: note: template argument deduction/substitution failed:
In file included from src/../inc/Tile.hpp:8:0,
from src/Tile.cpp:1:
src/../inc/ConstructableJson.hpp:23:3: note: mismatched types ‘_Tp [_Nm]’ and ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*’
for (auto obj : list()) {
^
In file included from /usr/include/c++/5/string:51:0,
from /usr/include/c++/5/bits/locale_classes.h:40,
from /usr/include/c++/5/bits/ios_base.h:41,
from /usr/include/c++/5/ios:42,
from /usr/include/c++/5/ostream:38,
from /usr/include/c++/5/iostream:39,
from src/../inc/Tile.hpp:4,
from src/Tile.cpp:1:
/usr/include/c++/5/bits/range_access.h:78:5: note: candidate: template<class _Container> decltype (__cont.end()) std::end(const _Container&)
end(const _Container& __cont) -> decltype(__cont.end())
^
/usr/include/c++/5/bits/range_access.h:78:5: note: template argument deduction/substitution failed:
/usr/include/c++/5/bits/range_access.h: In substitution of ‘template<class _Container> decltype (__cont.end()) std::end(const _Container&) [with _Container = std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*]’:
src/../inc/ConstructableJson.hpp:23:3: required from ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/bits/range_access.h:78:5: error: request for member ‘end’ in ‘__cont’, which is of pointer type ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >* const’ (maybe you meant to use ‘->’ ?)
src/../inc/ConstructableJson.hpp: In instantiation of ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’:
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/bits/range_access.h:68:5: note: candidate: template<class _Container> decltype (__cont.end()) std::end(_Container&)
end(_Container& __cont) -> decltype(__cont.end())
^
/usr/include/c++/5/bits/range_access.h:68:5: note: template argument deduction/substitution failed:
/usr/include/c++/5/bits/range_access.h: In substitution of ‘template<class _Container> decltype (__cont.end()) std::end(_Container&) [with _Container = std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*]’:
src/../inc/ConstructableJson.hpp:23:3: required from ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/bits/range_access.h:68:5: error: request for member ‘end’ in ‘__cont’, which is of pointer type ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*’ (maybe you meant to use ‘->’ ?)
In file included from /usr/include/c++/5/bits/range_access.h:36:0,
from /usr/include/c++/5/string:51,
from /usr/include/c++/5/bits/locale_classes.h:40,
from /usr/include/c++/5/bits/ios_base.h:41,
from /usr/include/c++/5/ios:42,
from /usr/include/c++/5/ostream:38,
from /usr/include/c++/5/iostream:39,
from src/../inc/Tile.hpp:4,
from src/Tile.cpp:1:
src/../inc/ConstructableJson.hpp: In instantiation of ‘ConstructableJsonHolder<T>::~ConstructableJsonHolder() [with T = Tile]’:
src/Tile.cpp:4:12: required from here
/usr/include/c++/5/initializer_list:99:5: note: candidate: template<class _Tp> constexpr const _Tp* std::end(std::initializer_list<_Tp>)
end(initializer_list<_Tp> __ils) noexcept
^
/usr/include/c++/5/initializer_list:99:5: note: template argument deduction/substitution failed:
In file included from src/../inc/Tile.hpp:8:0,
from src/Tile.cpp:1:
src/../inc/ConstructableJson.hpp:23:3: note: mismatched types ‘std::initializer_list<_Tp>’ and ‘std::map<std::__cxx11::basic_string<char>, Tile*, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, Tile*> > >*’
for (auto obj : list()) {
^
makefile:13*: la recette pour la cible «*obj/Tile.o*» a échouée
make: *** [obj/Tile.o] Erreur 1

Merci de votre aide !

[jo_link_noir]

Ça dit qu'il n'y a pas de fonction begin/end pour un pointeur. Pourquoi list() ne retourne pas une référence ? Au passage mettre le statique dans la fonction list() serait beaucoup plus facile.

Mais ce qui me choque vraiment est
1 - d'utiliser un membre statique alors que celui-ci semble être détruit par une instance ConstructableJsonHolder. Pourquoi ne pas le mettre en membre ?
2 - s'occuper de détruire manuelle les pointeurs alors qu'il existe std::unique_ptr.