[Python-Dev] PEP 246: lossless and stateless

[Raymond Hettinger]

> Ok.  I think we have identified two sorts of restrictions on the
> sorts of adaptations one may want to have:
> 
>   `stateless'  the adaptation may only provide a result which
>                does not maintain its own state
> 
>   `lossless'   the adaptation preserves all information available
>                in the original object, it may not discard state

+1 on having a provision for adapters to provide some meta-information
about themselves.  With these two key properties identified at the
outset, adapt calls can be made a bit more intelligent (or at least less
prone to weirdness).

There is some merit to establishing these properties right away rather
than trying to retrofit adapters after they've been in the wild for a
while.



 
> Since __conform__ and __adapt__
> would sprout two new arguments, it would make those writing adapters
> think a bit more about the kind of adapter that they are providing.

Using optional arguments may not be the most elegant or extensible
approach.  Perhaps a registry table or adapter attributes would fare
better.



Raymond Hettinger