curl_multi should not be copyable about curlcpp

[amerlyq]

Why functor? Why not directly std::unique_ptr<CURLM, curl_multi_cleanup> handle_; ? Any reasons I can't catch up with?

[ilyapopov]

No, that would not compile. Second argument of unique_ptr must be a type. It can be a function pointer type, like this:

unique_ptr<CURLM, int(*)(CURLM*)> handle_;

But then you have to provide concrete pointer at the construction:

curl_multi::curl_multi()
    : handle_(nullptr, curl_multi_cleanup)
{}

This way, the function pointer would be stored in the unique pointer object itself, unnecessarily taking space. With the functor, the call is resolved at compile time, and no additional space or time is spent.