Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!rutgers!usc!elroy.jpl.nasa.gov!cit-vax!ronen
From: ronen@cit-vax.Caltech.Edu (Ronen Barzel)
Newsgroups: comp.lang.c++
Subject: Re: Class member initialization proposal
Message-ID: <14589@cit-vax.Caltech.Edu>
Date: 13 Apr 90 22:18:07 GMT
References: <14560@cit-vax.Caltech.Edu> <1990Apr13.064548.1133@sjsumcs.sjsu.edu>
Reply-To: ronen@cit-vax.UUCP (Ronen Barzel)
Organization: California Institute of Technology
Lines: 30

In article <1990Apr13.064548.1133@sjsumcs.sjsu.edu> horstman@sjsumcs.SJSU.EDU (Cay Horstmann) writes:
>                             ...The only benefit would be to give the
>compiler a hint to factor out code common to all constructors. But you
>could do that manually with a member function. 

You can't do it in all cases.  From Lippman, sec 6.1 p.243: 
"The member initialization list is the only mechanism by which const
and reference class data members can be initialized."  Thus const and
reference initializations can't be factored out into a member function.

>HOWEVER, for static const this would indeed be very desirable:
I agree.  Even for static but non-const.  In summary, I think it's
desirable to specify an initialization for anything as part of (or at
least along with) its definition.  [Anybody care to argue with this claim?]

Along the same lines, it would be nice to specify default parameters
to base class constructors.  Again, this is something that can't be
factored out into a member function.  e.g.:

    OLD					NEW
    ----------------------		------------------------------
    class A : public B {		class A : public B(3,"foo") {
	A();				    A();
    };					};
    A::A() : B(3,"foo")			A::A()
    { /* body */ }			{ /* body */ }

Does g++ support this too?

-Ronen