On Jun 14, 2005, at 1:25 AM, Raymond Hettinger wrote:
>>>> By the way, whatever happened to "and while"? i.e.:
>>>>
>>>> while True:
>>>> data = inp.read(blocksize)
>>>> and while data:
>>>> out.write(data)
>>>>
>>>>
>>>
>>> My favourite version of this is
>>>
>>> while:
>>> data = inp.read(blocksize)
>>> gives data:
>>> out.write(data)
>>>
>>
>> Well, we could always just make iterator factories for the common
>> cases and stuff them in itertools. I do need to use this pattern
>> from time to time, but primarily for this exact use case, so an
>> "itertools.readby" or the like would probably solve this problem for
>> most people most of the time.
>>
>
> Doesn't work. You still need to be able to pass through the blocksize
> argument and the target bound method. To get what you want, there
> would
> need to be a new method in the file API. The reason is roughly
> similar
> to why we have iteritems as part of the mapping API and not as a
> standalone itertool.
>
> for data in inp.read(blocksize):
> . . .
Reality check?
def readby(inp, blocksize=1024):
while True:
data = inp.read(blocksize)
if not data:
break
yield data
for data in readby(inp, blocksize):
. . .
I always thought was that iteritems is part of the mapping API and
not as a standalone itertool because it is the *most primitive* way
to iterate over the key/value pairs. It is simply not implementable
without access to the private guts of the dict. That is simply not
the case here.
If you need an ultra-flexible (but less obvious) implementation you
should just use the sentinel version of the iter function as JP
demonstrated.
-bob
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