[Zope] Can't add "date" property to new ZClass

[Toby Dickenson]

On Mon, 11 Oct 1999 15:06:50 -0700, you wrote:

>I'm creating a brand new ZClass (called "PDFClass"). It's my first ZClass.
>I've just added the Common Instance Property Sheet (called "PDFProperties").
>Now I'm trying to add properties to that property sheet. I added one
>"string" property OK, but now when I add the "date" property "pub_date", I
>get this error:
>
>          Invalid Date-Time String

Are you planning to extract properties from PDF files? That's a task
on my to-do list too.


>Of course, the value is invalid -- I didn't put any value in the "Value"
>box, because this is a class property, and values only make sense when the
>class is instantiated, right?

This is a detail carried over from Python, where class attributes can
be used as default values for 'missing' instance attributes.

This is useful (once you know how it works ;-) if you have created
some instances before making a change to a class. The instances
automatically get the new attribute with the default value, and this
happens without any database transactions since their instance
attributes have not changed.


Hope this helps,


Toby Dickenson