I'm trying to allocate a list for each key of my std map, but using the new operator I obtain some errors (no predefined constructor is find and others), why?
My code is like this one:
std::map<QString, *std::list<ExecutionGUIObject*>> execEvtMap;
execEvtMap["t1"] = new std::list<ExecutionGUIObject*>;
*std::list<ExecutionGUIObject*>
is not a valid type and hence not a valid argument to the std::map template. You probably meant
std::list<ExecutionGUIObject*>*
which means 'pointer to list of pointers to ExecutionGUIObject objects'.
As stated by Frerich Raabe, it's a minor syntax error in your map declaration. But you gain nothing by allocating the std::list's dynamically, so why seek trouble ? Just use a map of lists.
std::map<QString, std::list<ExecutionGUIObject*>> execEvtMap;
// Creates a new (empty) list for key "t1" if one does not already exist.
void(execEvtMap["t1"]);
// Creates a new list for key "t1", or clears the existing one.
execEvtMap["t1"].clear();
// Erases a key and its list
execEvtMap.erase("t1");
If this maps owns the ExecutionGUIObject's, you'll want to tweak that too :
std::map<QString, std::list<std::unique_ptr<ExecutionGUIObject>>> execEvtMap;
std::list<...> &getList(QString key); ? Yes, same cost. In fact, you can only see it speed up by cutting down on the dynamic allocations. Plus, no wild owning raw pointers to manage.