Re: Partial classes

From:
Piyo <cybermax_69@yahoo.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 12 Mar 2007 05:41:59 GMT
Message-ID:
<HK5Jh.3727$JZ3.1131@newssvr13.news.prodigy.net>
Adrian Hawryluk wrote:

Sorry, is this better?

BTW still based on the example, only A is dependent
on B fully. B does not need a full include in the
header (in the .cpp yes but not the header). A forward
declaration of class A in B is sufficient in the header.
But I am sure you know this :)

<header file="A.h">
  #if !defined A_H
  # define A_H

  // Stub for forward referencing
  class A;

  # include ?B.h?

  class A
  {
    // Interface functions
    void f(B* b, B::b_e enums);
  ...
  };
  #endif
</header>

<header file="B.h">
  #if !defined B_H
  # define B_H

  // Stub for forward referencing
  class B;

  # include ?A.h?
  class B
  {
  public:
    enum b_e { enum1, enum2 };

    void f(A* a); ///< here is the dependent
    // Interface functions
  ...
  };
  #endif
</header>

As for the actual example, it would be too long and have lots of extra
non-relevant stuff, but trust me it does occur and has occurred at other
times before that.


I do understand that it does occur and based on your suggestions, I
would do:

1) Hopefully your compiler is smart to do empty base class optimization
to eliminate your overhead.

1. Base classes would have a explicit size of 1, adding a small amount
   of overhead.


Check this for reference about the optimization:
http://www.cantrip.org/emptyopt.html

2) doing the base class thing also kind of implies to me that you may
opt to namespace your enumerated independent of both class A and class
B and you can even reintroduce the enumerated type back into class B
if that is even necessary.

HTH

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