Anjanesh Lekshminarayanan wrote:
But how come a raise StopIteration in the next() method doesnt need to
be caught ? It works without breaking.
The for-loop looks for and catches StopIteration. It is an essential
part of what defines a finite iterator.
(Note, in 3.0, next is renamed __next__ in conformance with all other
special methods. In 2.6, the rename is optional, I believe.)
class twoTimes:
max = 10**10
def __init__(self, n):
self.__n = n
There is no reason to mangle the attribute name.
Max should be a parameter, and self.max = max added to the init.
def next(self):
if self.__n > self.max:
raise StopIteration
self.__n *= 2
return self.__n
Are you sure you do not want to return once the initial value of n
passed to init?
def __iter__(self):
return self
Once you understand the above, you can rewrite it as a generator function:
def two_times(num, stop):
while num < stop:
yield num
num *=2
The two last lines can be switches if desired.
t = twoTimes(5)
c = 0
print (t.next())
print (t.next())
for n in t:
print n
>>> print(list(two_times(5,687)))
[5, 10, 20, 40, 80, 160, 320, 640]
Terry Jan Reedy
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