在C ++中使用带有函子的头文件

Question

I am attempting to use functors in a larger-scope project. I managed to implement a functor when it was on its own, but I am having a lot of trouble figuring out where I define things in the header file (.h) vs the .ccp file so that I can access my functor in the rest of my program. When the functor is all together it appears as such:

class SpecialAttack {
public:
    SpecialAttack() {};
    virtual bool operator() (double timer) = 0;
};

class BallAttack : public SpecialAttack {
public:
    BallAttack() {};
    virtual bool operator() (double timer) { return (timer==0); }
};

class SpiderAttack : public SpecialAttack {
public:
    SpiderAttack() {};
    virtual bool operator() (double timer) { return true; }
};

double special_attack(double timer, SpecialAttack* func) {
    return (*func)(timer);
}

I cannot figure out how to break this up into the appropriate files so that I can then reference it in the rest of my code. What parts should i put in the .h file and what parts go in the .ccp file? Thanks!

Answer 1

Splitting functors between .hpp and .cpp files follows the same pattern of declaration and definition used for any class with member functions.

attack.hpp

#pragma once

class SpecialAttack {
public:
    SpecialAttack();
    virtual bool operator() (double timer) = 0;
};

class BallAttack : public SpecialAttack {
public:
    BallAttack();
    virtual bool operator() (double timer) override;
};

class SpiderAttack : public SpecialAttack {
public:
    SpiderAttack();
    virtual bool operator() (double timer) override;
};

attack.cpp

#include "attack.hpp"

SpecialAttack::SpecialAttack() {
}

BallAttack::BallAttack() {
}

/*virtual*/ bool BallAttack::operator() (double timer) /*override*/ {
    return (timer==0);
}

SpiderAttack::SpiderAttack() {
}

/*virtual*/ bool SpiderAttack::operator() (double timer) /*override*/ {
    return true;
}