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Re: ordering of constructors
On Fri, Apr 09, 2004 at 10:52:00AM -0400, Daniel Jacobowitz wrote:
> On Fri, Apr 09, 2004 at 03:33:20PM +0200, Gabriel Dos Reis wrote:
> > It is implementation-defined whether or not the dynamic
> > initialization (8.5, 9.4, 12.1, 12.6.1) of an object of namespace
> > scope is done before the first statement of main. If the
> > initialization is deferred to some point in time after the first
> > statement of main, *it shall occur before the first use of any
> > function or object defined in the same translation unit as the
> > object to be initialized*.
>
> Does that answer the question? I don't believe that it does. In this
> case, the initialization is _not_ deferred until after the first
> statement of main. Instead, we're before main executing global
> constructors.
>
> To honor your interpretation of that paragraph, we would have to check
> at the beginning of every external function in every translation unit
> containing static variables whether they had been initialized yet,
> which would be prohibitively expensive - and I'm pretty sure we don't
> do that.
It's worse than that; an attempt to provide the guarantee before main
is called fails in cases where constructors in file A.cpp depend on
the construction of objects in B.cpp and vice versa: an attempt to
provide the guarantee would cause a deadlock.