Re: How can i force my derivers to call a base function

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Wed, 19 Dec 2007 09:18:40 +0100
Message-ID:
<13mhkv9dp7csp28@corp.supernews.com>
* ManicQin:

Hi lets say I have the next situation
class base
{
pubic: ;)
  base() {}
  virtual ~base(){}
  virtual init()
    {//do init }
};

now i want that every deriver will call MY init function before he
init his class...
for some reasons I cannot put those calls in the cTor...

one thing that I thought of is
class base
{
 public:
    init()
      {
          //do base's init
          secondPhaseInit();
      }
protected:
      virtual secondPahseInit() = 0;
}

and then the deriver can only override secondPhaseInit and he needs to
go through my init .
But it's still not an idiot proof method... is there a way?


Your question is extremely unclear.

If it's just about how to achieve two-phase construction, the best is
probably to read up on class invariants in order to understand why that
is a generally a Bad Idea.

Otherwise, have a look at the FAQ, e.g. <url:
http://www.parashift.com/c++-faq-lite/strange-inheritance.html#faq-23.6>.

Cheers, & hth.,

- Alf

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