[Python-Dev] Generating nested data structures with blocks

[Walter Dörwald]

Reading PEP 340, it seems to me that blocks could be used for generating 
nested data structures:

def blist(list):
	def enter(parent=None):
		if parent:
			parent.append(self)
		yield self

x = blist()
block x.enter() as x:
	x.append(1)
	block blist().enter(x) as x:
		x.append(2)
	x.append(3)

print x

this should print [1, [2], 3]

For this to work, the scope of the block variable has to end with the 
end of the block. Currently the PEP leaves this unspecified.

Bye,
    Walter Dörwald