Grant Baillie wrote:
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.
Yes, good point -- it would be dangerous if anything in the same view
depended on those indexes (or filtercollections) during the time that
indexing is disabled... but if all we're doing within the "with"
statement is attribute assignment, and we do the index updates before we
start calling observers, I think it's safe, right?
...Bryan
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