[Python-Dev] Design question: call __del__ for cyclical garbage?

[Jack Jansen]

The __init__ rule for calling __del__ has me confused. Is this per-class or 
per-object?

I.e. what will happen in the following case:

class Purse:
	def __init__(self):
		self.balance = WithdrawCashFromBank(1000)

	def __del__(self):
		PutCashBackOnBank(self.balance)
		self.balance = 0

class LossyPurse(Purse):
	def __init__(self):
		Purse.__init__(self)
		 raise 'kaboo! kaboo!'

If the new scheme means that the __del__ method of Purse isn't called I think 
I don't like it. In the current scheme I can always program defensively:
	def __del__(self):
		try:
			b = self.balance
			self.balance = 0
		except AttributeError:
			pass
		else:
			PutCashBackOnBank(b)
but in a new scheme with a per-object "__del__ must be called" flag I can't...
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