[Zope-CMF] Re: [dev] RFC: Extensible propertysheet use cases

[yuppie]

Hi Michel!


Michel Pelletier wrote:
> On Wed, 2004-09-29 at 13:40, yuppie wrote:
>>Two reasons why I would prefer a new class:
>>
>>- The functions currently exposed in FactoryTypeInformation are mature 
>>and fool save compared to the proposed PropertySheets machinery. If you 
>>don't know exactly what you do, it is very likely that modifying the 
>>schema after creating instances of that type screws up your data.
> 
> 
> The instance property sheets can define a custom getProperty that checks
> against the type schema to see if it's changed.

And what happens if getProperty detects a schema change? It's easy to 
change the schema in a way that's hard or even impossible to propagate 
without data loss.

>>- FactoryTypeInformation is also used by Archetypes and CPSDocument. 
>>These have their own schema machinery that's not compatible with the 
>>PropertySheets machinery.
> 
> 
> That's a good reason for a new class, but by "not compatible" do you
> mean just different?  Or do thay actually conflict on the same
> attributes and break each other?

No. Don't think it breaks something. But it adds useless stuff that 
might confuse people.

>>TW: Against which CMF version is your patch? I tried it with HEAD, but 
>>that didn't work.
> 
> 
> Oops, this was developed against the customer site, 2.0.4.  I'll try and
> get a head version out soon.

Thanks. The link didn't show up on the TypeInfo properties tab. Don't 
know if other things are broken.


Cheers,
	Yuppie