Re: [Boost-users] pattern support for traversing inheritance chain

Subject: Re: [Boost-users] pattern support for traversing inheritance chain
From: Brian Budge (brian.budge_at_[hidden])
Date: 2012-11-07 18:24:15

Thanks for the remark Kris.  I had thought of that, but unfortunately, the
two-step approach is necessary since I'm using a handle-to-data approach.
 The actual pointers (objects) associated with the handles may change, and
the (possibly incremental) init needs to be re-run for the object.

  Brian

On Wed, Nov 7, 2012 at 3:17 PM, Krzysztof Czainski <1czajnik_at_[hidden]>wrote:

> 2012/11/8 Brian Budge <brian.budge_at_[hidden]>
>
>> Hi all -
>>
>> I have a case where I have a largeish inheritance hierarchy.  I will be
>> calling an initialization function on all objects before using them in some
>> fashion.
>>
>> Basically what I need to happen is when I call init() on a Foo the
>> following would occur:
>>
>> void Foo::init() {
>>     super::init();
>>     // now with the knowledge that anything I inherited is set up, I can
>> set myself up...
>> }
>>
>> It is not necessary for every call to implement init, in which case the
>> behavior should be that the call is propagated up the inheritance chain
>> (which it is by default in C++).
>>
>> In order to make this work, I need to write different code for "super" in
>> every class implementation, which is a bit error prone.  Even if I don't
>> copy/paste, my brain might be on autopilot and type something further up
>> the inheritance chain than it should be.  Alternatively, I could require
>> that each class provides a typedef for super, but I'm still relying on
>> myself to remember to call super's init function.
>>
>> Is there anything in boost that would support this kind of hierarchy
>> traversal (semi-)automatically?  If there is not, are there suggestions for
>> ways to implement this in a less error-prone fashion?
>>
>> Thanks,
>>   Brian
>>
>
> I think the constructors in C++ work the way you want init() to work. You
> probably use two-step initialization, don't you? Can you avoid it?
>
> Regards,
> Kris
>
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