I'm trying to do some testing with member function pointer. What is wrong with this code? The bigCat.*pcat(); statement doesn't compile.
class cat {
public:
void walk() {
printf("cat is walking \n");
}
};
int main(){
cat bigCat;
void (cat::*pcat)();
pcat = &cat::walk;
bigCat.*pcat();
}
More parentheses are required:
(bigCat.*pcat)();
^ ^
The function call (()) has higher precedence than the pointer-to-member binding operator (.*). The unary operators have higher precedence than the binary operators.
pcat does not name a member, it names the pointer-to-member declared as a local variable in main.
for_each-like algorithms that took a sequence of pointers and called a member function on each of the pointed-to objects. It saved me from having to use ugly function binder incantations. That was before lambda expressions made that a lot easier... if I were to rewrite all of that code, I'd probably use lambdas for most of the uses.
Today, the canonical way is using the std::invoke function template, especially in generic code. Please note, that the member function pointer comes first:
import <functional>;
std::invoke(pcat, bigCat);
What you get: Unified calling syntax for virtually anything, that is invocable.
Overhead: none.
