How can we distinguish between data member and nested class in a normal(non-template) class?

[Andy]

class Container
{
public:
static int X;
class X
{
public:
X()
{
std::cout << "X ctor" << std::endl;
}
};
};

void g()
{
// How can we access type Container::X here, since we cannot use
typename in normal class?
}

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[Miles Bader]

Andy <wangsi...@gmail.com> writes:

> class Container
> {
> public:
> static int X;
> class X

...

>
> How can we access type Container::X here, since we cannot use
> typename in normal class?

You can use "class Container::X", e.g.:

void g()
{
Container c;
class Container::X x;
c.X = 3;
}

-Miles

--
Inhumanity, n. One of the signal and characteristic qualities of humanity.

[Pavel Minaev]

On Dec 14, 9:39 am, Andy <wangsilian...@gmail.com> wrote:
> class Container
> {
> public:
> static int X;
> class X
> {
> public:
> X()
> {
> std::cout << "X ctor" << std::endl;
> }
> };
>
> };
>
> void g()
> {
> // How can we access type Container::X here, since we cannot use
> typename in normal class?
>
> }

Same as for similar case with namespace scope:

class C::X foo; // C::X is type here
int n = C::X; // C::X is static member here

Note that this won't compile in the first place:

class C {
static int X;
typedef int X;
};

so there's no issue with disambiguation in that case (where you
couldn't use class/struct/union tag).

[Yechezkel Mett]

On Dec 14, 7:39 pm, Andy <wangsilian...@gmail.com> wrote:
> class Container
> {
> public:
> static int X;
> class X
> {
> public:
> X()
> {
> std::cout << "X ctor" << std::endl;
> }
> };
>
> };
>
> void g()
> {
> // How can we access type Container::X here, since we cannot use
> typename in normal class?
>
> }

You are only allowed to use the name X for both the variable and the
class due to a backwards compatibility rule with C where the struct
names live in a different namespace to other names.

In other words what you have is equivalent to the following:

int X;
struct X;

The rule in this case is that the struct name is hidden. You can
explicitly refer to it with struct X or class X; in your case class
Container::X. And as a general rule, don't do that.

Yechezkel Mett