GCC-4.7 Compilazione

Question

Quando aggiungo l'ultima riga da questo frammento al mio codice di programma:

typedef std::set<Job> JobSet; 
typedef boost::shared_ptr<JobSet> JobSetPtr; 
JobSetPtr jobs_; 

jobs_->insert (job); // line 60 

ottengo questo errore:

g++-4.7 -o /home/kron/Software/Synchronizer/1.0/Main.o -c src/Main.cpp 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h: In instantiation of ‘bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Job]’: 
/usr/include/c++/4.7/bits/stl_tree.h:1285:4: required from ‘std::pair<std::_Rb_tree_iterator<_Val>, bool> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_insert_unique(const _Val&) [with _Key = Job; _Val = Job; _KeyOfValue = std::_Identity<Job>; _Compare = std::less<Job>; _Alloc = std::allocator<Job>]’ 
/usr/include/c++/4.7/bits/stl_set.h:415:29: required from ‘std::pair<typename std::_Rb_tree<_Key, _Key, std::_Identity<_Key>, _Compare, typename _Alloc::rebind<_Key>::other>::const_iterator, bool> std::set<_Key, _Compare, _Alloc>::insert(const value_type&) [with _Key = Job; _Compare = std::less<Job>; _Alloc = std::allocator<Job>; typename std::_Rb_tree<_Key, _Key, std::_Identity<_Key>, _Compare, typename _Alloc::rebind<_Key>::other>::const_iterator = std::_Rb_tree_const_iterator<Job>; std::set<_Key, _Compare, _Alloc>::value_type = Job]’ 
src/Configuration.hpp:60:27: required from here 
/usr/include/c++/4.7/bits/stl_function.h:236:22: error: no match for ‘operator<’ in ‘__x < __y’ 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: candidates are: 
In file included from /usr/include/c++/4.7/bits/stl_algobase.h:65:0, 
       from /usr/include/c++/4.7/bits/char_traits.h:41, 
       from /usr/include/c++/4.7/ios:41, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_pair.h:218:5: note: template<class _T1, class _T2> bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&) 
/usr/include/c++/4.7/bits/stl_pair.h:218:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::pair<_T1, _T2>’ 
In file included from /usr/include/c++/4.7/bits/stl_algobase.h:68:0, 
       from /usr/include/c++/4.7/bits/char_traits.h:41, 
       from /usr/include/c++/4.7/ios:41, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_iterator.h:299:5: note: template<class _Iterator> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&) 
/usr/include/c++/4.7/bits/stl_iterator.h:299:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::reverse_iterator<_Iterator>’ 
In file included from /usr/include/c++/4.7/bits/stl_algobase.h:68:0, 
       from /usr/include/c++/4.7/bits/char_traits.h:41, 
       from /usr/include/c++/4.7/ios:41, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_iterator.h:349:5: note: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&) 
/usr/include/c++/4.7/bits/stl_iterator.h:349:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::reverse_iterator<_IteratorL>’ 
In file included from /usr/include/c++/4.7/string:54:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/basic_string.h:2566:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/include/c++/4.7/bits/basic_string.h:2566:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::basic_string<_CharT, _Traits, _Alloc>’ 
In file included from /usr/include/c++/4.7/string:54:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/basic_string.h:2578:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*) 
/usr/include/c++/4.7/bits/basic_string.h:2578:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::basic_string<_CharT, _Traits, _Alloc>’ 
In file included from /usr/include/c++/4.7/string:54:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/basic_string.h:2590:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/include/c++/4.7/bits/basic_string.h:2590:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: mismatched types ‘const _CharT*’ and ‘Job’ 
In file included from /usr/include/c++/4.7/vector:65:0, 
       from src/Main.cpp:2: 
/usr/include/c++/4.7/bits/stl_vector.h:1372:5: note: template<class _Tp, class _Alloc> bool std::operator<(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&) 
/usr/include/c++/4.7/bits/stl_vector.h:1372:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::vector<_Tp, _Alloc>’ 
In file included from /usr/include/c++/4.7/set:60:0, 
       from src/Configuration.hpp:4, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_tree.h:873:5: note: template<class _Key, class _Val, class _KeyOfValue, class _Compare, class _Alloc> bool std::operator<(const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&, const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&) 
/usr/include/c++/4.7/bits/stl_tree.h:873:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>’ 
In file included from /usr/include/c++/4.7/set:61:0, 
       from src/Configuration.hpp:4, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_set.h:721:5: note: template<class _Key, class _Compare, class _Alloc> bool std::operator<(const std::set<_Key, _Compare, _Alloc>&, const std::set<_Key, _Compare, _Alloc>&) 
/usr/include/c++/4.7/bits/stl_set.h:721:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::set<_Key, _Compare, _Alloc>’ 
In file included from /usr/include/c++/4.7/set:62:0, 
       from src/Configuration.hpp:4, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_multiset.h:702:5: note: template<class _Key, class _Compare, class _Alloc> bool std::operator<(const std::multiset<_Key, _Compare, _Alloc>&, const std::multiset<_Key, _Compare, _Alloc>&) 
/usr/include/c++/4.7/bits/stl_multiset.h:702:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::multiset<_Key, _Compare, _Alloc>’ 
In file included from /usr/include/c++/4.7/list:64:0, 
       from /usr/include/boost/algorithm/string/std/list_traits.hpp:15, 
       from /usr/include/boost/algorithm/string/std_containers_traits.hpp:20, 
       from /usr/include/boost/algorithm/string.hpp:18, 
       from src/Configuration.hpp:9, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_list.h:1659:5: note: template<class _Tp, class _Alloc> bool std::operator<(const std::list<_Tp, _Alloc>&, const std::list<_Tp, _Alloc>&) 
/usr/include/c++/4.7/bits/stl_list.h:1659:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::list<_Tp, _Alloc>’ 
In file included from /usr/include/c++/4.7/deque:65:0, 
       from /usr/include/boost/algorithm/string/find_format.hpp:14, 
       from /usr/include/boost/algorithm/string/replace.hpp:22, 
       from /usr/include/boost/algorithm/string.hpp:25, 
       from src/Configuration.hpp:9, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_deque.h:274:5: note: template<class _Tp, class _Ref, class _Ptr> bool std::operator<(const std::_Deque_iterator<_Tp, _Ref, _Ptr>&, const std::_Deque_iterator<_Tp, _Ref, _Ptr>&) 
/usr/include/c++/4.7/bits/stl_deque.h:274:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::_Deque_iterator<_Tp, _Ref, _Ptr>’ 
In file included from /usr/include/c++/4.7/deque:65:0, 
       from /usr/include/boost/algorithm/string/find_format.hpp:14, 
       from /usr/include/boost/algorithm/string/replace.hpp:22, 
       from /usr/include/boost/algorithm/string.hpp:25, 
       from src/Configuration.hpp:9, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_deque.h:282:5: note: template<class _Tp, class _RefL, class _PtrL, class _RefR, class _PtrR> bool std::operator<(const std::_Deque_iterator<_Tp, _RefL, _PtrL>&, const std::_Deque_iterator<_Tp, _RefR, _PtrR>&) 
/usr/include/c++/4.7/bits/stl_deque.h:282:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::_Deque_iterator<_Tp, _RefL, _PtrL>’ 
In file included from /usr/include/c++/4.7/deque:65:0, 
       from /usr/include/boost/algorithm/string/find_format.hpp:14, 
       from /usr/include/boost/algorithm/string/replace.hpp:22, 
       from /usr/include/boost/algorithm/string.hpp:25, 
       from src/Configuration.hpp:9, 
       from src/Main.cpp:5: 
/usr/include/c++/4.7/bits/stl_deque.h:1947:5: note: template<class _Tp, class _Alloc> bool std::operator<(const std::deque<_Tp, _Alloc>&, const std::deque<_Tp, _Alloc>&) 
/usr/include/c++/4.7/bits/stl_deque.h:1947:5: note: template argument deduction/substitution failed: 
In file included from /usr/include/c++/4.7/string:50:0, 
       from /usr/include/c++/4.7/bits/locale_classes.h:42, 
       from /usr/include/c++/4.7/bits/ios_base.h:43, 
       from /usr/include/c++/4.7/ios:43, 
       from /usr/include/c++/4.7/ostream:40, 
       from /usr/include/c++/4.7/iostream:40, 
       from src/Main.cpp:1: 
/usr/include/c++/4.7/bits/stl_function.h:236:22: note: ‘const Job’ is not derived from ‘const std::deque<_Tp, _Alloc>’ 
make: *** [/home/kron/Software/Synchronizer/1.0/Main.o] Error 1 

È colpa mia? Se sì, cosa ho fatto di sbagliato? Se no, qualcuno ha lo stesso errore?

Answer 1

Sembra che tu non abbia fornito una definizione di operatore < per confrontare due oggetti di tipo Job.

Quando si inserisce un oggetto in std::set, il contenitore deve conoscere la posizione in cui deve inserire l'elemento, per il quale è necessario confrontare l'oggetto da inserire con gli elementi già presenti nel set. Per farlo usa l'operatore < che immagino tu non abbia fornito. std::set<Job> semplicemente non sa come confrontare due oggetti di tipo Job.

Quindi è possibile fornire operator< per la classe Job.

O, in alternativa, definire questo funtore per confrontare Job oggetti:

struct JobComparer 
{ 
    bool operator()(Job const &j1, Job const &j2) 
    { 
     //compare j1 and j2 and return true or false 
    } 
}; 

quindi utilizzarlo come:

typedef std::set<Job, JobComparer> JobSet; 

Oppure, si potrebbe specializzarsi std::less come explained here.

si poteva vedere questo argomento:

• std::set with user defined type, how to ensure no duplicates

Answer 2

Nawaz fornito una risposta semplice, ma penso che merita una più completa.

A set di oggetti, in C++, è un contenitore ordinato senza duplicati. Per poter ordinare oggetti usa un secondo parametro template diverso dall'oggetto stesso: un functor il cui compito è confrontare due oggetti. Utilizza anche un terzo parametro per l'allocazione della memoria, inutile qui.

Quando si utilizza un set vi fornirà due parametri:

struct NameComparator { 
    template <typename T> 
    bool operator()(T const& left, T const& right) { 
     return left.name() < right.name(); 
    } 
}; 

std::set<Job, NameComparator> JobSet; 

Il comparatore fornito dovrebbe definire una qualche nozione di ordine.In sostanza, pensare a come < lavoro per due interi:

• è irriflessiva: x < x mai stive
• è antisimmetrica: se x < y poi y < x è falso
• è transitiva: se x < y e y < z poi x < z

Poiché si tratta di una relazione così comune, tale funzione è presente nella libreria standard: template <typename T> struct std::less;, che funziona s per qualsiasi tipo T con date due istanze è possibile utilizzare l'operatore <.

E così com'è, il secondo parametro di set, che non è stato indicato in modo esplicito, per impostazione predefinita è std::less<TypeOfObjectInSet>. Il che significa che funziona appena fuori dalla scatola se fornito con oggetti per i quali è definito <.

Pertanto, si dispone di 3 soluzioni.

Se gli oggetti ammettono una relazione di ordine "naturale", è possibile definire operator< o specializzare std::less. Altrimenti, se hai solo bisogno di una relazione di ordine per questo set, puoi fornire il tuo comparatore.

Nota: se l'ordine è non richiesto, è possibile utilizzare uno unordered_set. Richiede hashing e una relazione di uguaglianza.