cannot convert from 'const _Ty2' to 'const std::function

Question

I have a bottleneck to my code:

Code:

void CSomeClass::SomeMethod(const std::string& method, const std::function<void (CMyObject)>& handler)
{
    //
}

void CSomeClass::RegisterHandler(const web::http::method& Method, const MethodFn& Fn)
{
    m_methodHandlerMap[Method] = Fn;
}

MethodHandlerMap CMyClass::GetHandlerMap() const
{
    return m_methodHandlerMap;
}

using MethodFn = std::function<void(CMyObject&)>;
using MethodHandlerMap = std::unordered_map<std::string, MethodFn>;
MethodHandlerMap m_methodHandlerMap;

// code block
{
    CSomeClass sc;
    sc.RegisterHandler("AMethod", std::bind(&CSomeClassExtended::AMethod, this, std::placeholders::_1));
}

// code block
{
    auto localMap = m_pMyClass->GetHandlerMap();

    std::for_each(localMap.begin(), localMap.end(),
                [this](const auto& handlePair)
                {
                    m_object.SomeMethod(handlePair.first, handlePair.second);   // ERROR !!! see below
                });
}

and the error I got:

// error C2664: 'void CSomeClass::SomeMethod(const std::string &, const std::function<void (CMyObject)> &)': cannot convert argument 2 from 'const _Ty2' to 'const std::function<void (CMyObject)> &'
// note: Reason: cannot convert from 'const _Ty2' to 'const std::function<void (CMyObject)>'

the fact is that I write:

    std::for_each(localMap.begin(), localMap.end(),
                [this](const auto& handlePair)
                {
                    m_object.SomeMethod(handlePair.first, nullptr);     // is compiling ok
                });

I didn't write the lambda correctly ? What I have done wrong ?

Answer 1

You are passing std::function<void (CMyObject&)> to a function that expects std::function<void (CMyObject)> (note the extra ampersand). These are distinct, unrelated types.

Answer 2

Check this:

void CSomeClass::SomeMethod( const std::string& method, const std::function<void( CMyObject& )>& handler )...

or:

void CSomeClass::SomeMethod( const std::string& method, const MethodFn & handler )...

Answer 3

I cannot change CSomeClass::SomeMethod signature because is a part of a library. But I would take care of what you have told me.

You told me both of you the source of the error, how can accept both answers as solution ? I will take on of you, but consider that both helped me to solve it ! Thanks a lot !