list comprehension question
steve at REMOVE-THIS-cybersource.com.au
Fri May 8 20:39:37 EDT 2009
On Thu, 07 May 2009 13:28:10 -0400, J Kenneth King wrote:
> Steven D'Aprano <steven at REMOVE.THIS.cybersource.com.au> writes:
>> On Wed, 06 May 2009 09:48:51 -0400, J Kenneth King wrote:
>>> Emile van Sebille <emile at fenx.com> writes:
>>>> On 5/5/2009 9:15 AM J Kenneth King said...
>>>>> List comprehensions can make a reader of your code apprehensive
>>>>> because it can read like a run-on sentence and thus be difficult to
>>>>> parse. The Python documentation discourages their use and I believe
>>>>> for good reason.
>>>> Can you provide a link for this? I'd like to see specifically what's
>>>> being discouraged, as I'd be surprised to find routine usage frowned
>>> "If you’ve got the stomach for it, list comprehensions can be nested.
>>> They are a powerful tool but – like all powerful tools – they need to
>>> be used carefully, if at all."
>> How does this discourage the use of list comprehensions? At most, it
>> warns that complicated list comps are tricky. Complicated *anything*
>> are tricky.
> They are tricky and need to be used carefully, *if at all*.
> IMO this means that if there's a way to do it without a nested list
> comprehension, then that solution should be preferred.
Earlier, you claimed that list comps in general were discouraged:
"List comprehensions can make a reader of your code apprehensive because
it can read like a run-on sentence and thus be difficult to parse. The
Python documentation discourages their use and I believe for good reason."
Emile said "I'd be surprised to find routine usage frowned upon", giving
you the opportunity to correct his (mis)understanding. You failed to do
so, which I took as meaning that you agreed that routine usage of simple
list comps were frowned upon. Now you're talking about *nested* list
comps. You started off (apparently) objecting to list comps in general,
because they "can" make readers apprehensive. Now you seem to be saying
that it's only the complicated, overly-dense ones which rightly make
readers apprehensive which you object to.
I suppose we're making progress if we agree that the Python docs warn
against unnecessarily complicated nested list comps. Whether it
discourages as well as warns is a matter of interpretation. But there's
certainly no sign that list comps as a general technique are discouraged
just because overly-complicated list comps are tricky to read. The same
can be said about *any* piece of code.
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