Fix statistics.py after the Decimal.as_integer_ratio() change

[skrah]

BPO	25974
Nosy	@rhettinger, @terryjreedy, @mdickinson, @abalkin, @stevendaprano, @skrah, @berkerpeksag, @serhiy-storchaka
Files	statistics_as_integer_ratio.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/stevendaprano'
closed_at = <Date 2016-05-06.12:02:09.068>
created_at = <Date 2015-12-29.12:49:31.259>
labels = ['type-bug', 'library', 'release-blocker']
title = 'Fix statistics.py after the Decimal.as_integer_ratio() change'
updated_at = <Date 2016-05-06.12:02:09.066>
user = 'https://github.com/skrah'

bugs.python.org fields:

activity = <Date 2016-05-06.12:02:09.066>
actor = 'berker.peksag'
assignee = 'steven.daprano'
closed = True
closed_date = <Date 2016-05-06.12:02:09.068>
closer = 'berker.peksag'
components = ['Library (Lib)']
creation = <Date 2015-12-29.12:49:31.259>
creator = 'skrah'
dependencies = []
files = ['41446']
hgrepos = []
issue_num = 25974
keywords = ['patch', '3.5regression']
message_count = 7.0
messages = ['257178', '257184', '257186', '257190', '257210', '262826', '264968']
nosy_count = 10.0
nosy_names = ['rhettinger', 'terry.reedy', 'mark.dickinson', 'belopolsky', 'steven.daprano', 'skrah', 'python-dev', 'berker.peksag', 'serhiy.storchaka', 'johnwalker']
pr_nums = []
priority = 'release blocker'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue25974'
versions = ['Python 3.6']

[skrah]

Here's a fix for the fallout from bpo-25928. I've set it to
release blocker to make sure we don't forget.

[serhiy-storchaka]

LGTM.

I haven't tested that "type(x) is float or type(x) is Decimal" is faster than alternatives ("type(x) in (float, Decimal)", or "isinstance(x, (float, Decimal))", or "hasattr(x, 'as_integer_ratio')") and believe you have tested this.

[skrah]

No, I haven't done any benchmarks. In a quick test type(x) == float
does not seem any faster than isinstance(x, float), so perhaps we
could reduce the try/except complexity.

[skrah]

The clear winner for float and Decimal is hasattr(x, 'as_integer_ratio').
The other types are a bit disadvantaged if the lookup fails, but they
go through additional try/excepts anyway.

[serhiy-storchaka]

I believe the current code is well-weighed compromise that optimize different cases ranged for their frequency of occurrence (floats, ints, decimals, fractions, subclasses of int, float, etc and independed numeric types). And new addition unlikely will change the balance too much, but we have to be aware. If Steven have no something to add, the patch LGTM.

[skrah]

Ping. Just a reminder that it would be nice to get this into 3.6-alpha-1. :)

[berkerpeksag]

statistics_as_integer_ratio.diff has been committed in 7b2fafd78c1d.