On Fri, Apr 6, 2018 at 10:37 AM, Steven D'Aprano email@example.com wrote:
On Thu, Apr 05, 2018 at 05:31:41PM -0700, Ethan Furman wrote:
On 04/05/2018 03:24 PM, Peter O'Connor wrote:
Well, whether you factor out the loop-function is a separate issue. Lets say we do:
smooth_signal = [average = compute_avg(average, x) for x in signal from average=0]
Is just as readable and maintainable as your expanded version, but saves 4 lines of code. What's not to love?
It is not readable and it is not Python (and hopefully never will be).
Be fair. Strip out the last "from average = 0" and we have little that isn't either in Python or is currently being proposed elsewhere. Change the syntax for assignment within the comprehension to one of the preferred syntax variants from last month's "Statement local name bindings" thread, and we have something that is strongly being considered:
[(average := compute_avg(average, x)) for x in signal] [(compute_avg(average, x) as average) for x in signal]
All we need now is a way to feed in the initial value for average. And that could be as trival as assigning a local name for it:
average = 0
before running the comprehension.
That would only work if the comprehension is executed in the same context as the surrounding code, instead of (as currently) being in a nested function. Otherwise, there'd need to be an initializer inside the comprehension - but that can be done (although it won't be particularly beautiful).