Sybren Stuvel wrote:
> Paul Rubin enlightened us with:
>>> height = 0
>>> for block in stack:
>>> if block.is_marked():
>>> print "Lowest marked block is at height", height
>>> break
>>> height += block.height
>>> else:
>>> raise SomeError("No marked block")
>>
>> all_heights = [block.height for block in stack if block.is_marked()]
>> if all_heights:
>> height = sum(all_heights)
>> else:
>> raise SomeError("No marked block")
>>
>> Alternatively (lower memory usage for large list):
>>
>> all_heights = (block.height for block in stack if block.is_marked())
>> try:
>> height = all_heights.next()
>> height += sum(all_heights)
>> except StopIteration:
>> raise SomeError("No marked block")
>
> I must say that the for/else construct is a LOT more readable than the
> rewritten alternatives.
I like
def blocks_til_mark(stack):
for block in stack:
if block.is_marked():
return
yield block
raise SomeError
height = sum(block.height for block in blocks_til_mark(stack))
Peter
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