Re: Exchanging objects between programs with different inheritance hierarchies

[Simon Wright <simon@pushface.org>]

tmoran@acm.org writes:

> > You almost never have to override 'Input, 'Output. 'Read and 'Write,

> I think it's "almost always" rather than "almost never".  If it's an
> object of any complexity, in a program that's more than just quick
> and dirty, you probably need to code your own routines to have
> better control over just how things are laid out in the stream, and
> how fast it runs.

(The following is "as I understand it")

'Input, 'Output use bounds, discriminants or tags to control exactly
what 'Read, 'Write routines get called. So you _must_ get 'Read,
'Write right.

Of course I agree that you may need control over how bounds,
discriminants or tags are written, in which case you'll need to
specify 'Input, 'Output as well. But it's not a 'must'.