Can lambda functions be recursive?

Question

Possible Duplicate:
Recursive lambda functions in c++0x

Here is a plain old recursive function:

int fak(int n)
{
    return (n <= 1) ? 1 : n * fak(n - 1);
}

How would I write such a recursive function as a lambda function?

[](int n) { return (n <= 1) ? 1 : n * operator()(n - 1); }
// error: operator() not defined

[](int n) { return (n <= 1) ? 1 : n * (*this)(n - 1); }
// error: this wasn't captured for this lambda function

Is there any expression that denotes the current lambda so it can call itself recursively?

Answer 1

Yes, they can. You can store it in a variable and reference that variable (although you cannot declare the type of that variable as auto, you would have to use an std::function object instead). For instance:

std::function<int (int)> factorial = [&] (int i) 
{ 
    return (i == 1) ? 1 : i * factorial(i - 1); 
};

Otherwise, no, you cannot refer the this pointer from inside the body of the lambda.