Re: using a class inside a class.

kwikius wrote:
> On Apr 28, 7:33 pm, "Jim Langston" <tazmas...@[EMAIL PROTECTED]
> wrote:
>
>> All I can tell you is I've done this exact same thing in the past
>> successfully in both Microsoft Visual C++ .net 2003 and DevC++.  Here
is
>> something that compiles sucessfully in Microsoft Visual C++ .net 2003:
>>
>> #include <list>
>>
>> class CFoo
>> {
>> private:
>>     std::list<CFoo> m_children;
>>
>> };
>>
>> int main()
>> {
>>     CFoo Foo;
>>
>> }
>>
>> No warnings, no errors.
>>
>> I don't know why your version of gcc is complaining, I don't think it
>> should, AFAIK this is perfectly legal, although I haven't read the
standard
>> on it.
> 
>  IMO gcc is correct. You could have a list of pointers or refs to CFoo
> but not recursive types. One workaround *may* be to use a typedef
> alias for CFoo. That may fool gcc, but I think its technically correct
> to call this an error.
> 
Why?  The class declares m_children to be a list of CFoo.  It does not
attempt to use any members of std::list that require a complete type.

In effect, it's just like writing

#include <list>

class X;

class CFoo
{
private:
    std::list<X> m_children;
};

class X {};

int main()
{
    CFoo Foo;
}

The complete class definition is not required until std::list's default
constructor is instantiated in main().

-- 
Ian Collins.