Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c++
Subject: Re: Static initialization
Keywords: static initialize virtual
Message-ID: <722@taumet.com>
Date: 11 May 91 19:19:36 GMT
References: <1991May10.063358.15955@ccu1.aukuni.ac.nz>
Organization: Taumetric Corporation, San Diego
Lines: 30

gkean@ccu1.aukuni.ac.nz (Graham Kean;;g_kean) writes:

>Both Zortech C++ and Borland C++ give an error at the
>'{1,2,3}' in the following example:

>class TESTCLASS
>    {
>    public:
>	int a,b,c;
>	virtual void testfunc();
>    };
>void TESTCLASS::testfunc() {}
>TESTCLASS test = {1,2,3};

The C++ rule is that a class may be statically intialized using C-style
initialization syntax as long as it doesn't have "class-like" features.
Class-like features require a constructor to be called, which is not
supported by the C syntax.  You can look up in the ARM to find the
full details of what is allowed.  The easiest way to remember it is that
a class can be initialized with C syntax if it looks like a C struct.
Otherwise, use a constructor.  (This is overly restrictive, but will
keep you out of trouble.)

In your specific instance, a class with virtual functions requires a
(pointer to the) table of the virtual functions to be part of the class,
something done by the constructor.  The '={1,2,3}' syntax precludes
calling a contructor, and hence is illegal.
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com