rails/rails — pull request #11856 by dchelimsky (2013-08-12 17:57:34+00:00)
Title: Refactor Duration#inspect

In preparing https://github.com/rails/rails/pull/11855, it took me a
minute to understand what was going on due to naming (parts refers first
to an attr_accessor, then to a local, and is then reassigned), but also
because the iterator conditionally builds nulls and then removes them.

I refactored to something much more functional-looking that I find
easier to read, but you may or may not. If you do, great! Enjoy! If
not, oh well, I tried. Can't win 'em all :)

Rationale:

* no name conflict between local var and attr_accessor
* no reassignment of local var
* algorithm spelled out in steps
* unused items in initial list filtered out early
* empty-list case handled early instead of reassigning local var
* no duplication of formatting strings ("0 seconds")

Benchmarks (after PR #11855 merged):

10000.times do
1.second.inspect
end

original #inspect
0.350000 0.000000 0.350000 ( 0.354709)
0.330000 0.000000 0.330000 ( 0.331885)
0.330000 0.000000 0.330000 ( 0.334441)

refactored #inspect
0.340000 0.000000 0.340000 ( 0.340080)
0.340000 0.010000 0.350000 ( 0.345069)
0.330000 0.000000 0.330000 ( 0.335873)

10000.times do
(1.day + 1.month + 2.minutes + 1.day).inspect
end

original #inspect
0.400000 0.000000 0.400000 ( 0.403027)
0.400000 0.000000 0.400000 ( 0.403781)
0.390000 0.000000 0.390000 ( 0.387596)

refactored #inspect
0.400000 0.010000 0.410000 ( 0.399792)
0.400000 0.000000 0.400000 ( 0.404145)
0.400000 0.000000 0.400000 ( 0.403820)