can't access parent classes private member (VC6)

[Gernot Frisch]

This code works on VC7.1. But VC6 refuses to compile.

class foo
{
class bar
{
friend class foo;
foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

error C2248: 'poo' : cannot access private member declared in class
'foo'
What can I doo?

--
-Gernot
int main(int argc, char** argv) {printf
("%silto%c%cf%c gl%ssic%ccom%c" , "ma", 58, 'g', 64, "ba", 46, 10);}

_______________ _______________ __________
Looking for a good game? Do it yourself!
GLBasic - you can do
www.GLBasic.com

[peter koch]

Gernot Frisch wrote:

This code works on VC7.1. But VC6 refuses to compile.

class foo
{
class bar
{
friend class foo;
foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

error C2248: 'poo' : cannot access private member declared in class
'foo'
What can I doo?

You allow foo access to bar, but let bar access foo.

/Peter
[snip]

[Victor Bazarov]

Gernot Frisch wrote:

This code works on VC7.1. But VC6 refuses to compile.

class foo
{
class bar
{
friend class foo;
foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

error C2248: 'poo' : cannot access private member declared in class
'foo'
What can I doo?

Declare classs bar as a friend of foo:

class foo
{
class bar; // forward-declaration of a member
friend class bar;

class bar
{
friend class foo;
// ^^^^^^^^^^^^^^^ ^
// do you really need this here?

foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

The other option is to abandon this outdated compiler for good.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Rolf Magnus]

Gernot Frisch wrote:

This code works on VC7.1. But VC6 refuses to compile.

class foo
{
class bar
{
friend class foo;
foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

error C2248: 'poo' : cannot access private member declared in class
'foo'
What can I doo?

The same you can do to make any other class access that member: Make the
member public or make bar a friend of foo.

[Gernot Frisch]

"Victor Bazarov" <v.********@com Acast.net> schrieb im Newsbeitrag
news:e3******** **@news.datemas .de...

Gernot Frisch wrote:

This code works on VC7.1. But VC6 refuses to compile.

class foo
{
class bar
{
friend class foo;
foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

error C2248: 'poo' : cannot access private member declared in class
'foo'
What can I doo?

Declare classs bar as a friend of foo:

class foo
{
class bar; // forward-declaration of a member
friend class bar;

class bar
{
friend class foo;
// ^^^^^^^^^^^^^^^ ^
// do you really need this here?

foo & m_f;
public:
bar(foo & f) : m_f(f) {}
void wii()
{
m_f.poo(); // #error C2248
}
} m_bar;

void poo() {}

public:
foo() : m_bar(*this) {}
};

The other option is to abandon this outdated compiler for good.

This works. But now I have more questions.
class foo
{
class bar;
friend class bar;
class bar{};
};

Now, foo can access bar's private members - am I wrong? I'm a bit
confused now.

[Abdo Haji-Ali]

Gernot Frisch wrote:

This works. But now I have more questions.
class foo
{
class bar;
friend class bar;
class bar{};
};

Now, foo can access bar's private members - am I wrong? I'm a bit
confused now.

No, it's the other way around. bar can now access foo's private (and
protected) members

Abdo Haji-Ali
Programmer
In|Framez

[Gernot Frisch]

"Abdo Haji-Ali" <ah***@inframez .com> schrieb im Newsbeitrag
news:11******** **************@ v46g2000cwv.goo glegroups.com.. .

Gernot Frisch wrote:

This works. But now I have more questions.
class foo
{
class bar;
friend class bar;
class bar{};
};

Now, foo can access bar's private members - am I wrong? I'm a bit
confused now.

No, it's the other way around. bar can now access foo's private (and
protected) members

Thank you. I never had to use "friend" before.

[Lyell Haynes]

> This works. But now I have more questions.

class foo < { class bar;
friend class bar;
class bar{};
};

Now, foo can access bar's private members - am I wrong? I'm a bit
confused now.

Declaring a class as your friend means that you let _them_ access
private members of _you_, not the other way around.

Think of it like this: I give you keys to my front door, so that you
have acess to my house. I declare you as my friend by giving you the
keys. You can declare me as your friend, but that doesn't give you
access to my house. Only I can say whether you have access or not.

class A {};
class B { friend class A }; <-- A can access private members of B

Lyell

[Gernot Frisch]

Think of it like this: I give you keys to my front door, so that you
have acess to my house. I declare you as my friend by giving you the
keys. You can declare me as your friend, but that doesn't give you
access to my house. Only I can say whether you have access or not.

That's nice to remember for good.

[red floyd]

Gernot Frisch wrote:

"Abdo Haji-Ali" <ah***@inframez .com> schrieb im Newsbeitrag
news:11******** **************@ v46g2000cwv.goo glegroups.com.. .

Gernot Frisch wrote:

This works. But now I have more questions.
class foo
{
class bar;
friend class bar;
class bar{};
};

Now, foo can access bar's private members - am I wrong? I'm a bit
confused now.

No, it's the other way around. bar can now access foo's private (and
protected) members

Thank you. I never had to use "friend" before.

Easy way to remember:

Only you and your friends can play with your private parts.