Re: Self pointer in limited record

[Jean-Pierre Rosen <rosen@adalog.fr>]

Adam Beneschan a �crit :

> The trouble is, I can think of several occasions in which I assumed an
> object could only have one instance---and then later found reason to
> wish I had written it so that there could be two.
> 
> No, this doesn't happen in all cases.  But it seems to me it happens
> often enough that one should carefully examine any assumption that
> there can be only one instance.  Or be prepared to go back and make
> some major changes later.
> 
If you implemented your singleton as a package, it is quite an automatic 
transformation:

- Add a (normally private) type to the specification
- Implement it as a record whose components are all the global (state) 
variables of the package
- Add a parameter of this type to every subprogram provided by the 
package, and in the bodies, change the references to  the global 
variables to the corresponding field of the new parameter.

-- 
---------------------------------------------------------
            J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr