On 22 Mar, 2007, at 11:58, Bryan Stearns wrote:
Phillip J. Eby wrote:
In discussion with Morgen, Bear, and John, we've determined that
the optimum way to support fast dump and reload with proper
support for multiple inheritance and type changes due to sharing,
is to get rid of custom __init__ methods for Item subclasses.
[...]
The second feature is a new 'schema.initialValues()' function that
you can call in the body of a class to define how the class'
attributes should be initialized. For example:
class ContentItem(Item):
...
schema.initialValues(
createdOn = lambda self: datetime.now()
)
In other words, keyword arguments are used for the attribute
names, and the values are functions taking the item as an argument
and returning the desired attribute value. The attributes are
*not* limited to schema attributes; they can be transient
attributes or even properties, and they override any values
defined in a superclass or in the attribute's "initialValue"
aspect. This also eliminates the need for __init__ to supply
default values for keyword arguments or to change default
attribute values established by base classes.
The order that individual attributes will be set in is not
guaranteeed, but they are *all* set before your __setup__ method
is called. Any keyword arguments passed to __init__ will prevent
that attribute value from being calculated - it'll just be set
from the keyword before __setup__ is called.
Can you please wrap this initialization with:
with view.observersDeferred():
with view.reindexingDeferred():
# change item class here
# do initialization here
so that observers don't fire until the state of the object is
consistent? (I don't know whether disabling indexing is important,
but I don't think it'll hurt...)
I think, but am not 100% sure, the reindexingDeferred() is dangerous,
since setting attributes (in general) can cause reindexing of
FilterCollections that depend on those attributes.
--Grant
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