How can I use lambda function within itself?

Question

I have this code and don\'t know if what I would like to achieve is possible.

_acceptor.async_accept(
    _connections.back()->socket(),
    [this](const boos         


        

Answer 1

You have to store a copy of the lambda in itself, using std::function<> (or something similar) as an intermediary:

std::function<void(const boost::system::error_code&)> func;
func = [&func, this](const boost::system::error_code& ec)
{
    _connections.push_back(std::make_shared<TcpConnection>(_acceptor.get_io_service()));
    _acceptor.async_accept(_connections.back()->socket(), func);
}

_acceptor.async_accept(_connections.back()->socket(), func);

But you can only do it by reference; if you try to capture it by value, it won't work. This means you have to limit the usage of such a lambda to uses were capture-by-reference will make sense. So if you leave this scope before your async function is finished, it'll break.

Your other alternative is to create a proper functor rather than a lambda. Ultimately, lambdas can't do everything.