Re: [Dev-C++] Re: Design decision in C++

[Per W. <pw...@ia...>]

I haven't looked at any Singleton<DataType> class doing any instance
pointer offset hack.

The sample code I sent for a singleton object was just a very fiew lines
of manually added code to the class in question. 100% valid C++ without
any typecasts.

/Per W

On Thu, 11 Mar 2004, Doug MacDonald wrote:

> Per and Kevin,
>
> Thanks for your advice.
>
> My ambivalence wrt the Singleton<DataType> class is in part due to the
> instance pointer offset hack, which seems to introduce a risk of
> implementation dependency: are base and derived classes always included
> in a standard order with offsets that never vary from compiler to
> compiler?.  Further, the instance pointer adjustment involves pointer
> <-> int casts that are a bit ugly, despite the elegance of Singleton as
> seen from the outside.
>
> But I take your points as to the limited desirability of fully static
> classes.
>
> (I guess declaring a top-level static _instance_ of a class is a
> different matter, and is useful, e.g., when there is no C++ main
> routine, as was the case in a former project of mine at my last employer.)
>
> --Doug
>
>
>
>