C/C++ Nested Classes in C++: Protected Access Error

[dodo]

Hopefully this sort of questions will soon be answered in the tutorial (good effort, Dduardo!), but for the time being, this one is not.

I have the following scheme:

class Foo {

...
​

protected:

struct PartOne {

...
​

};

struct PartTwo {

...
PartOne* someFunction ();
​

};​

};
​

And I get a complaint of PartTwo's being unable to access a protected symbol (PartOne) from Foo.

A "friend struct PartTwo;" right after the "protected:" indication doesn't seem to solve the problem, as I expected. (I'd prefer not to take the two Parts out of Foo, as independent structures.) Where am I thinking wrong?

Thanks very much in advance.

---
Edit: If this helps... actually I'm not getting the error in the declaration (like the above), but when later writing the implementation of 'someFunction', which spells like:

Foo::PartOne* Foo::PartTwo::someFunction () &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// <--- offending line
{

...
​

}​

The MS VC++ 6.0 compiler says,
'PartOne' : cannot access protected struct declared in class 'Foo'

 

[dduardo]

You might be running into the infamous nested problems with the Microsoft compiler. You'll need to either upgrade to version VC++ 7.0 or use GCC.

Here is some example code that works under GCC:

#include <iostream>

using namespace std;

class foo {

protected:

        struct foo1 {
                int x;
        };

        struct foo2 {
                foo1 myfunction(void) ;
        };

public:
        void myfunction2(void) ;

};

void foo::myfunction2(void) {
foo2 test ;
test.myfunction();
}

foo::foo1 foo::foo2::myfunction(void) {
cout << "hello\n";
}

int main (void) {

foo testme;

testme.myfunction2();

}

 

[dodo]

I should've suspected when the compiler issued the error message TWICE for the same line. :)

Thank you; I'll try to workaround it.

---
Edit:
Confirmed - I get the same error (thrice :)

error C2248: 'foo1' : cannot access protected struct declared in class 'foo'
​

on line 27 of your program,

foo::foo1 foo::foo2::myfunction(void) {
​

Thanks for crosschecking.

 

[dduardo]

Microsoft makes great mice and keyboards, but stay away from their compiler like the plague.

 

[master_coda]

I should've suspected when the compiler issued the error message TWICE for the same line. :)

Thank you; I'll try to workaround it.

Is there some reason you have to use the VC++ 6.0 compiler? It pains me to see someone work around a compiler flaw; particularly for such a horrible compiler.

 

[dodo]

It's the one at hand, and my workplace's choice. Nothing I can't do. (Corporate decisions here.) Thanks for caring.

Edit: typo.