Re: mutual class dependencies

From:
Grizlyk <grizlyk1@yandex.ru>
Newsgroups:
comp.lang.c++
Date:
Fri, 25 Jan 2008 20:15:47 -0800 (PST)
Message-ID:
<5d68fbdf-7f1c-4d4a-a427-b665e187436d@e23g2000prf.googlegroups.com>
Grizlyk wrote:

//forward declarations
class B;
class A;

class A
{
public:
    A()
    {
           }
        A& SetContext(B::TContext eContext)


You can pass eContext by reference
            A& SetContext(B::TContext& eContext)


Well, looks like useless advice here, because B::TContext must be
declared. You can not declare B::TContext like this (i do not know
why)

class B;
//using B::C;
//class B::C;

but you can use template<> to delay declaration

template<typename T=B>
class A
{
public:
    A& SetContext(T::TContext& eContext);
};

template<typename T> //(T=B is not allowed)
void ::foo(T::TContext& c)
{
A<T> a;
    a.SetContext(c);
}

class B
{
public:
    //can be declared only for references
    class TContext;
};

void ::boo(B::TContext& c)
{
    foo<B>(c);
}

or remove declaration of TContext into separated class


And yet, instead of using B::TContext& reference, you can move body of
SetContext function outside of class A scope and place the body after
B::TContext complete declaration, but the declaration of SetContext
with eContext passed by value will touch you in code like this

void ::foo(B::TContext& b)
{
A a;
    a.SetContext(b);
}

if the code ::foo will be placed befor B::TContext complete
declaration.

Maksim A. Polyanin
http://grizlyk1.narod.ru/cpp_new

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