Using auto specifier in std::function and lambdas - c++

Question

I have a class named Handler wich stores some lambdas. What I want to do is to have a std::vector of std::function that stores all my events, for exemple. I really can't figure out why lambdas doesn't work as I expected.
Here's the handler.h:
class Handler
{
public:
Handler();
~Handler();
void Register(const char* outcome, std::function<auto()> lambda);
void Trigger(const char* outcome);
private:
std::vector<int> identifier;
std::vector<char*> outcome;
std::vector<std::function<auto()>> func;
};
And handler.cpp:
Handler::Handler()
{
//ctor stuff here
}
Handler::~Handler()
{
this->func.clear();
this->outcome.clear();
this->identifier.clear();
//...
}
void Handler::Register(const char* outcome, std::function<auto()> lambda)
{
static int identifier = 0;
identifier++;
this->outcome.push_back((char*)outcome);
this->identifier.push_back(identifier);
this->func.push_back(lambda);
//Sort outcome
}
void Handler::Trigger(const char * outcome)
{
int i;
for (i = 0; i < this->identifier.size(); i++)
{
if (!strcmp(outcome, this->outcome.at(i)))
break;
}
this->func[i]();
}
However, if I specify lambdas in a Handler::Register it wont let me throwing no suitable user-defined conversion from "lambda []void ()->void" to "std::function<auto()> exists. In this example I use void return type but other types also error, I don't understant why can't the template from std::function deduce it out, if it is what's happening.
Handler* events = new Handler();
events->Register("Up", [=]() -> void { //Error here!
//do stuff
//return something?
});
Is there any other way to do this, like without overloading Handler::Register?

Answer 1

auto is not a type, so std::function<auto()> is not a type either. From how you are using it, std::function<void()> is probably what you want.
There are other problems with your code, as noted in the comments, so I would change Handler to this
class Handler
{
public:
Handler();
// default ~Handler is fine
void Register(std::string outcome, std::function<void()> lambda);
void Trigger(const std::string & outcome outcome) const;
void Trigger(std::size_t index) const;
private:
using Outcomes = std::map<std::string, std::function<void()>/*, custom string comparator ?*/>;
std::vector<Outcomes::iterator> identifier;
Outcomes outcomes;
};
void Handler::Register(std::string outcome, std::function<void()> func)
{
auto emplaced = outcomes.emplace(std::move(outcome), std::move(func));
identifier.push_back(emplaced.first);
}
void Handler::Trigger(const std::string & outcome) const
{
outcomes.at(outcome)();
}
void Handler::Trigger(std::size_t index) const
{
identifier[index]->second();
}