Strange error using a class array for a thread C++ - c++

Question

I'm trying to do a Thread calling the cook class through a vector but I don't know to do it correctly. Here is my code:
for (int i = 0; i < _numCooks; i++) {
std::thread threadObj(this->_cooks[i].nextOrder, void);
_threads.push_back(threadObj);
}
_cooks is a vector of a class and the function that I am trying to make a thread of is:
bool cooks::nextOrder()
{
Margarita margarita(_cookOrder[0].pizzaSize);
Regina regina(_cookOrder[0].pizzaSize);
Fantasia fantasia(_cookOrder[0].pizzaSize);
Americana americana(_cookOrder[0].pizzaSize);
if (_cookOrder.empty())
return (false);
switch (_cookOrder[0].pizzaType) {
case plazza::Margarita:
return (makeOrder(margarita));
break;
case plazza::Regina:
return (makeOrder(regina));
break;
case plazza::Fantasia:
return (makeOrder(fantasia));
break;
case plazza::Americana:
return (makeOrder(americana));
break;
default:
return (false);
}
}
however when I try to compile I get this:
kitchen/kitchen.cpp: In member function ‘void
Kitchen::make_pizza(std::__cxx11::string, std::__cxx11::string, Ipc)’:
kitchen/kitchen.cpp:148:59: error: expected primary-expression before
‘void’
std::thread threadObj(this->_cooks[i].nextOrder, void);
^~~~ kitchen/kitchen.cpp:148:63: error: invalid use of non-static member
function ‘bool cooks::nextOrder()’
std::thread threadObj(this->_cooks[i].nextOrder, void);
^ In file included from kitchen/kitchen.hpp:17,
from kitchen/kitchen.cpp:5: kitchen/cooks.hpp:32:10: note: declared here
bool nextOrder();
^~~~~~~~~ In file included from /usr/include/c++/8/x86_64-redhat-linux/bits/c++allocator.h:33,
from /usr/include/c++/8/bits/allocator.h:46,
from /usr/include/c++/8/string:41,
from /usr/include/c++/8/bits/locale_classes.h:40,
from /usr/include/c++/8/bits/ios_base.h:41,
from /usr/include/c++/8/ios:42,
from /usr/include/c++/8/ostream:38,
from /usr/include/c++/8/iostream:39,
from kitchen/../pizza/IPizza.hpp:23,
from kitchen/../pizza/APizza.hpp:11,
from kitchen/kitchen.hpp:8,
from kitchen/kitchen.cpp:5: /usr/include/c++/8/ext/new_allocator.h: In instantiation of ‘void
__gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = cooks; _Args = {const cooks&}; _Tp = cooks]’: /usr/include/c++/8/bits/alloc_traits.h:475:4: required from ‘static
void std::allocator_traits
::construct(std::allocator_traits >::allocator_type&, _Up*, _Args&& ...) [with _Up = cooks; _Args = {const cooks&}; _Tp = cooks;
std::allocator_traits >::allocator_type =
std::allocator]’ /usr/include/c++/8/bits/stl_vector.h:1079:30:
required from ‘void std::vector<_Tp, _Alloc>::push_back(const
value_type&) [with _Tp = cooks; _Alloc = std::allocator;
std::vector<_Tp, _Alloc>::value_type = cooks]’
kitchen/kitchen.cpp:36:30: required from here
/usr/include/c++/8/ext/new_allocator.h:136:4: error: use of deleted
function ‘cooks::cooks(const cooks&)’ { ::new((void )__p)
_Up(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from kitchen/kitchen.hpp:17,
from kitchen/kitchen.cpp:5: kitchen/cooks.hpp:21:7: note: ‘cooks::cooks(const cooks&)’ is implicitly deleted because the
default definition would be ill-formed: class cooks
^~~~~ kitchen/cooks.hpp:21:7: error: use of deleted function ‘std::basic_ofstream<_CharT, _Traits>::basic_ofstream(const
std::basic_ofstream<_CharT, _Traits>&) [with _CharT = char; _Traits =
std::char_traits]’ In file included from
kitchen/../plazza.hpp:15,
from kitchen/kitchen.hpp:13,
from kitchen/kitchen.cpp:5: /usr/include/c++/8/fstream:778:7: note: declared here
basic_ofstream(const basic_ofstream&) = delete;
^~~~~~~~~~~~~~ In file included from /usr/include/c++/8/vector:62,
from kitchen/../pizza/IPizza.hpp:24,
from kitchen/../pizza/APizza.hpp:11,
from kitchen/kitchen.hpp:8,
from kitchen/kitchen.cpp:5: /usr/include/c++/8/bits/stl_construct.h: In instantiation of ‘void
std::_Construct(_T1, _Args&& ...) [with _T1 = cooks; _Args =
{cooks}]’: /usr/include/c++/8/bits/stl_uninitialized.h:83:18:
required from ‘static _ForwardIterator
std::__uninitialized_copy<_TrivialValueTypes>::__uninit_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = std::move_iterator; _ForwardIterator = cooks*; bool
_TrivialValueTypes = false]’ /usr/include/c++/8/bits/stl_uninitialized.h:134:15: required from
‘_ForwardIterator std::uninitialized_copy(_InputIterator,
_InputIterator, _ForwardIterator) [with _InputIterator = std::move_iterator; _ForwardIterator = cooks*]’
/usr/include/c++/8/bits/stl_uninitialized.h:289:37: required from
‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator,
_InputIterator, _ForwardIterator, std::allocator<_Tp>&) [with _InputIterator = std::move_iterator; _ForwardIterator = cooks*; _Tp = cooks]’
/usr/include/c++/8/bits/stl_uninitialized.h:311:2: required from
‘_ForwardIterator
std::__uninitialized_move_if_noexcept_a(_InputIterator,
_InputIterator, _ForwardIterator, _Allocator&) [with _InputIterator = cooks*; _ForwardIterator = cooks*; _Allocator =
std::allocator]’ /usr/include/c++/8/bits/vector.tcc:447:6:
required from ‘void std::vector<_Tp,
_Alloc>::_M_realloc_insert(std::vector<_Tp, _Alloc>::iterator, _Args&& ...) [with _Args = {const cooks&}; _Tp = cooks; _Alloc =
std::allocator; std::vector<_Tp, _Alloc>::iterator =
__gnu_cxx::__normal_iterator >; typename std::_Vector_base<_Tp, _Alloc>::pointer = cooks*]’
/usr/include/c++/8/bits/stl_vector.h:1085:4: required from ‘void
std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp =
cooks; _Alloc = std::allocator; std::vector<_Tp,
_Alloc>::value_type = cooks]’ kitchen/kitchen.cpp:36:30: required from here /usr/include/c++/8/bits/stl_construct.h:75:7: error: use of
deleted function ‘cooks::cooks(const cooks&)’
{ ::new(static_cast(__p)) _T1(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make: *** [: kitchen/kitchen.o] Error 1
Is there any way to fix it?

Answer 1

According to this, the first argument to a std::thread constructor should meet the Callable concept. You then pass the subsequent arguments for the Callable as additional arguments to the constructor.
You're passing a member function. You need an instance of the class to call the method on, which you're not providing. This is what this error should mean to you.
error: invalid use of non-static member function ‘bool cooks::nextOrder()’
It's probably easiest to use a lambda ie.
for (int i = 0; i < _numCooks; i++) {
_threads.emplace_back([&cook = _cooks[i]]() {
cook.nextOrder();
});
}