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Re: Virtual functions in constructors. Is it possible?

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Alf P. Steinbach /Usenet ha scritto:
> * Anonymous, on 02.07.2011 01:19:
>>> See the FAQ
>>>
>>> <url: 
>>> http://www.parashift.com/c++-faq-lite/strange-inheritance.html#faq-23.6>
>>
>> That is an ugly solution in my opinion.
> 
> It's not "a" solution, it's a discussion of the possible ways in current 
> C++.

Ok, to be precise, the ways mentioned in the FAQ have the following 
limitations:

"In this variation, the code that is creating the object *explicitly 
executes both phases*. When executing Phase I, the code creating the 
object either knows the object's exact class (e.g., new Derived() or 
perhaps a local Derived object), or doesn't know the object's exact 
class (e.g., the virtual constructor idiom or some other factory). The 
"doesn't know" case is strongly preferred when you want to make it easy 
to plug-in new derived classes."

and


"The next approach does not rely on a two-phase initialization, instead 
using a second hierarchy whose only job is to house methods foo() and 
bar(). *This approach doesn't always work, and in particular it doesn't 
work in cases when foo() and bar() need to access the instance data 
declared in Derived*, but it is conceptually quite simple and clean and 
is commonly used."

In a way or the other static member functions are used there, which make 
the approaches just "ugly".

They key to the *perfect solution* is to profit by the lifetime of 
temporary objects passed to constructors: you can invoke a virtual 
function init() after an object has been constructed by calling it from 
a destructor of a temporary object passed to the constructor of the 
class that has to be initialized.

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Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-02 00:19 +0200
  Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-02 00:37 +0200
    Re: Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-02 01:19 +0200
      Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-02 08:50 +0200
        Re: Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-02 10:50 +0200
          Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-02 11:17 +0200
            Re: Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-02 11:25 +0200
              Re: Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-02 11:31 +0200
              Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-02 12:00 +0200
              Re: Virtual functions in constructors. Is it possible? Werner <werasm@gmail.com> - 2011-07-04 01:10 -0700
                Re: Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-04 20:41 +0200
                Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-04 21:35 +0200
                Re: Virtual functions in constructors. Is it possible? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-07-04 23:59 +0200
                Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-05 11:09 +0200
                Re: Virtual functions in constructors. Is it possible? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-07-05 13:15 +0200
                Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-05 14:51 +0200
                Re: Virtual functions in constructors. Is it possible? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-07-05 19:55 +0200
                Re: Virtual functions in constructors. Is it possible? Anonymous <anonymous@no.net> - 2011-07-05 20:46 +0200
                Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-05 21:23 +0200
                Re: Virtual functions in constructors. Is it possible? Werner <werasm@gmail.com> - 2011-07-06 00:14 -0700
  Re: Virtual functions in constructors. Is it possible? Virchanza <virtual@lavabit.com> - 2011-07-05 14:58 -0700
    Re: Virtual functions in constructors. Is it possible? "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-07-06 01:28 +0200

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