What does ::* mean in C++?

Question

What does

 private:
    BOOL (LASreader::*read_simple)();

mean?

It's from LAStools, in lasreader.hpp

BOOL is a typedef bool (from mydefs.hpp), but I don't know what this line is declaring, specifically the ::* (double colon asterisk), and that it looks like a function call.

Answer 1

It's a pointer to member function. Specifically, read_simple is a pointer to a member function of class LASreader that takes zero arguments and returns a BOOL.

From the example in the cppreference:

struct C {
    void f(int n) { std::cout << n << '\n'; }
};
int main()
{
    void (C::*p)(int) = &C::f; // p points at member f of class C
    C c;
    (c.*p)(1); // prints 1
    C* cptr = &c;
    (cptr->*p)(2); // prints 2
}

Answer 2

BOOL (LASreader::*read_simple)();

read_simple is a pointer to a member function of class LASreader that takes no arguments and returns a BOOL.