Re: Typed streams.

[Maciej Stachowiak <mjs eazel com>]

Michael Meeks <michael@helixcode.com> writes:

> Hi there,
> 
> 	I was just about to use the stream typing information,
> and I came to the conclusion that it can't do what I want =)
> What I need is to be able to store the type that a stream
> serialized to so that, should I not have the correct object
> ( with the same OAFIID ) to re-hydrate it, that I can do an
> oaf query and fall back to some other type. Hence I need either:
> 
> void save (in Bonobo::Stream stream, inout ContentType type)
>                                      ^^^^^
>            raises (WrongDataType);
> 
> 	Or; given the general consensus that inout parameters
> are evil and error prone:
> 
> ContentType save (in Bonobo::Stream stream,
>                   in ContentType type)
>                   ^^
>                   raises (WrongDataType);
> 
> 	This will nicely solve the problem; however, I'm not
> stopping here, several object [ particularly containers ] will
> need to serialize to a storage. The question is; is it worth
> storing the 'Type' of a Storage ? This would imply that more
> than 1 object was capable of reading a Storage structure; I
> can't think off hand of any circumstances where that would
> happen, indeed it would seem to me that if you don't have the
> object that wrote the storage you are stuffed. If other people
> think differently, we should put typing information onto
> storages.
> 

It might be that you at least have objects which can generically view
Storages (something that unpacks it, or browses it like a filesystem,
etc).

 - Maciej