Cannot access private member declared in one class BUT I can in another class

[wh1t3crayon]

So I have an ImageManager class, Board class, and Box class. In Board.h I can declare ImageManager imgr; and in Board's constructor I can use imgr and its functions and such. However, in Box.h when I try and declare ImageManager imgr; I get the error "cannot access member declared in class ImageManager". Both declarations are under private, and exactly the same, but one doesn't work. Can anybody help? Also, is there a way to only have one instance of ImageManager?

[LB]

You have not provided enough information for us to know what the problem is - please provide a minimal example that has the same error, or at the very least paste your code.

As for only having one ImageManager, you can have Board and Box take a reference to an ImageManager in their constructors and then you can construct them both from the same ImageManager. Don't use a singleton though; as a community we've agreed it's more of an anti-pattern.

[wh1t3crayon]

@LB
Board.h:

#pragma once
#include "stdafx.h"
#include <vector>
#include "Box.h"
#include "SFML/Graphics.hpp"
#include "ImageManager.h"

class Board{
public:
	Board();
	~Board();

	std::vector<Box> &GetBoxes();

	sf::Sprite GetGameBoard();
private:
	sf::Sprite gameBoard;

	std::vector<Box> boxes;

	ImageManager imgr;
};

and Board's constructor:

Board::Board(){
	imgr.AddResourceDirectory("images/");
	//error checking, images/ is indeed in the vector
	//std::cout << imgr.GetResourceDirectory()[0];

	gameBoard.setTexture(imgr.GetImage("t3board.png"));
}

This works. Now Box.h:

#pragma once
#include "stdafx.h"
#include "SFML/Graphics.hpp"
#include <vector>
#include "ImageManager.h"

class Box{
public:
	Box();
	~Box();

	void SetDrawn(bool drawn);
	bool GetDrawn();

	void SetShape(char shape);
	sf::Sprite GetShape();

	std::string GetName();
private:
	sf::Sprite shape;
	bool drawn;

	std::string name;

	ImageManager imgr;
};

and Box's constructor:

Box::Box(){
	static int namei = 0;
	namei++;
	name = "box" + std::to_string(namei);

	imgr.AddResourceDirectory("images/");
}

I get a compiler error: Error 3 error C2248: 'ImageManager::ImageManager' : cannot access private member declared in class 'ImageManager' Box.h

I don't know why it works for Board.h but not for Box.h

[LB]

I'll bet you anything it's trying to implicitly access the copy constructor of ImageManager when you try to copy a Box into the vector. Using a reference would definitely solve the problem.

[wh1t3crayon]

Alright thanks, I think I'll try using just one ImageManager with references like you said. But where would the one instance of ImageManager be? In my game engine class? In the ImageManager class?

[LB]

I assume you create a single instance of some class in your main function, right? Put the ImageManager instance in that class.

[wh1t3crayon]

@LB

#include "stdafx.h"
#include "Engine.h"

int _tmain(int argc, _TCHAR* argv[])
{
	Engine e;
	e.Go();
	return 0;
}

That's all my main function does, just call the game loop. What would I need to change?

[LB]

LB wrote:

I assume you create a single instance of some class in your main function, right? Put the ImageManager instance in that class.

Having reread that thoroughly, what do you think you're doing on line 6? ;p

Put the ImageHandler instance inside your Engine class.

[wh1t3crayon]

Right, sorry the wording eluded my grasp. Anyways, having done that, how do I access this ImageManager from my other classes? The details of this new problem are in my post here: http://stackoverflow.com/questions/25676303/how-do-i-implement-my-imagemanager?
But essentially, I just want to know how to pass my ImageManager around my whole program from one instance of it.

[LB]

Have your other classes take references to it via their constructors.

As for your problem,
http://www.cplusplus.com/articles/Gw6AC542/

[wh1t3crayon]

@LB

Board::Board(){
	ImageManager &imgr;
	//e.GetManager().AddResourceDirectory("images/");
	//error checking, images/ is indeed in the vector
	//std::cout << imgr.GetResourceDirectory()[0];

	//gameBoard.setTexture(e.GetManager().GetImage("t3board.png"));
}

the semicolon is highlighted, saying "the variable imgr requires an intitializer". I'm sorry i'm not getting this, but it's just not coming to me. In Engine.h, under public, I have declared ImageManager imgr;. What would be the correct way to do this?

[LB]

The reference to ImageManager needs to be a parameter passed to the constructor and needs to be a class member.

struct Example
{
    Example(ImageManager &im)
    : imgr(im)
    {
    }

private:
    ImageManager &imgr;
};

[wh1t3crayon]

@LB Ok, sorry for not understanding. So I've done exactly that, but I'm still getting an error.
Board.h:

#include "Box.h"
#include "SFML/Graphics.hpp"
#include "ImageManager.h"

class ImageManager;

class Board{
public:
	Board(ImageManager &im);
	~Board();

	std::vector<Box> &GetBoxes();

	sf::Sprite GetGameBoard();
private:
	sf::Sprite gameBoard;

	ImageManager &imgr;

	std::vector<Box> boxes;
};

Board.cpp:

#include "stdafx.h"
#include "Board.h"

Board::Board(ImageManager &im) : imgr(im){
	im.GetManager().AddResourceDirectory("images/");
	//error checking, images/ is indeed in the vector
	//std::cout << imgr.GetResourceDirectory()[0];

	//gameBoard.setTexture(e.GetManager().GetImage("t3board.png"));
}

"im" is underlined, saying that im has no member GetManager(). This is because the compiler isn't acually seeing im as an ImageManager object, correct? What do I do from here?

[mutexe]

This is because the compiler isn't acually seeing im as an ImageManager object, correct

No. It's saying that because it can't find a GetManager() method inside your ImageManager class.

can you post that class header?

edit: From your previous code snippets i'm guessing you want to do this maybe:

im.AddResourceDirectory("images/");

In other words you don't need to call GetManager(), as 'im' is your manager object.
I'm just guessing though..

[wh1t3crayon]

Oh wow, it is definitely a Monday.. GetManager() was what I had in my Engine in my other failed attempt to solve this. Anyways, if I declare the actual imgr, how do I pass that off as a constructor when I create a board object?
I.e. in Engine.h I declare Board board:

#pragma once
#include "stdafx.h"
#include "SFML/Graphics.hpp"
#include "ImageManager.h"
#include "Board.h"
#include <iostream>
#include "Box.h"

class Engine{
public:
	Engine();
	~Engine();

	void Go();
private:
	void ProcessInput();
	void Update();
	void Render();

	void FillVector();

	ImageManager imgr;

	Board board(ImageManager &imgr)

So is &imgr the same imgr that was declared in the previous line? Also, how do I declare a Board object in Engine? Because I used to just have Board board; which makes an object, but with my modified constructor how do I declare this object?

[LB]

Remove line 24.

Line 22: ImageManager &imgr'

Line 11: Engine(ImageManager &im);

[wh1t3crayon]

But if imgr is also a reference, when is the acual object made? I did the changes you made, and here's Engine's constructor:

Engine::Engine(ImageManager &im){
	window.create(sf::VideoMode(260, 260, 32), "Tic Tac Toe");
	FillVector();
	Board board(ImageManager &im);
}

The opening brace is underlined, throwing the error "Engine::Engine(ImageManager &im)" provides no initializer for: reference member "Engine::imgr""

Also, in functions for Engine, board is still undefined:

void Engine::ProcessInput(){
	while(window.pollEvent(event)){
		switch(event.type){
		case sf::Event::Closed:
			window.close();
			break;
		}
		if(sf::Mouse::isButtonPressed(sf::Mouse::Left)){
			sf::Vector2i localMousePos = sf::Mouse::getPosition(window);
			int xc = localMousePos.x;
			int yc = localMousePos.y;
			if(xc <= 80){
				if(yc <= 80){
					board.GetBoxes()[1].SetDrawn(true);
				}

board left of GetBoxes() throws the error that board is undefined. I'm clearly missing something here, but what?

[LB]

Sorry I hastily misread your code. Ignore my previous post.

What was line 24 trying to do?

[wh1t3crayon]

In short, line 24 is trying to create a classwide Board object in my Engine class. I could do this before without using a constructor, but now I have to pass an ImageManager parameter through board's constructor, so board becomes not an object

[LB]

Line 24 looks like a function, not an object. Did you mean this instead?

Board board {imgr};