you could set a version as a Class attribute (not a data(instance) attribute), and get __setstate__ to check this against a version stored as a data(instance attribute). If they are different, then apply the upgrades to the instance and update the instance version to the current class version. If they are already the same, then you simply pass through :-) Terry Hancock wrote:
Hi all, I need to check for upgrades and plugins from existing instances of a web application, but the process is going to be fairly intensive, and I don't want it to get called too often.
Basically I need for it to be called any time the product is refreshed or Zope restarted. This means that it should get called on each instance whenever the source files are (re-)interpreted and imported.
If I just put this into __setstate__, I'm afraid it will get called rather more frequently than that, but I'm not familiar enough with it to know how much of a problem that's likely to be. Obviously just using the __setstate__ hook would be the easiest solution.
Is there a better hook to use?
If not, I had considered giving my class a class property based on the date, and then checking that in __setstate__ to determine if any further work should be done:
class MyClass(...): import_date = DateTime()
def __init__(self, ...): self.current_import_date = self.import_date
def __setstate__(self, state): if self.import_date != self.current_import_date: pass # Actually do my update work here self.current_import_date = self.import_date
In the absence of a standard solution, this seems like the simplest approach. Is this the way to go, or am I overlooking some "batteries" somewhere?
Obviously the idea is to allow my instances to take advantage of newly installed plugins after a simple restart or refresh instead of having to create new instances every time something is changed (which would get to be a royal PITA in production use).
Cheers, Terry
-- Terry Hancock ( hancock at anansispaceworks.com ) Anansi Spaceworks http://www.anansispaceworks.com
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