That is, for any String string, does the following hold?
string.pluralize == string.pluralize.pluralize
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hoffm
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2What happened when you tried it? – Don Roby Feb 29 '12 at 19:24
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1@Don Roby: You mean, by checking for every possible string? – Niklas B. Feb 29 '12 at 19:25
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I meant for a reasonable set, as in Ryan Bigg's answer. – Don Roby Feb 29 '12 at 19:29
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Try person. It might return person -> people -> peoples, since people is a legitimate plural of people. – Alexander Corwin Feb 29 '12 at 19:29
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2Person doesn't break. Added it to my answer. – Ryan Bigg Feb 29 '12 at 19:30
2 Answers
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pluralize is NOT idempotent. I can prove it by example (courtesy of a personal Facebook posting that hit some language geeks).
"taxi".pluralize
=> "taxis"
"taxis".pluralize
=> "taxes"
"taxi".pluralize.pluralize
=> "taxes"
So "taxi" (the thing that drives you around) to "taxis" (an arrangement or order) to "taxes" (the proper pluralization of "taxis"). I'm sure there are other examples, but they are certainly hard to come by.
Not looking for score or acceptance on this answer, but I couldn't really fit this nicely into the comments on Ryan's post.
Marc Talbot
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1As of Rails 5 (and maybe earlier?), this counterexample no longer works. `"taxi".pluralize` => `"taxis"` and `"taxi".pluralize.pluralize` => `"taxis"` – hoffm Oct 19 '17 at 14:55
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What happens if I want to pluralize taxis? Probably still the right call though. – Marc Talbot Oct 20 '17 at 01:07
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I cannot think of a case where it wouldn't.
I just tried the following words and it doesn't change after a second pluralizaation. However, some of them do "break" in interesting ways because of two reasons: 1) Rails' pluralization rules are actually quite dumb and 2) English is hard.
- analysis -> analyses -> analysis
- media -> media -> media
- news -> news -> news
- cactii -> cactiis -> cactiis
- criterion -> criterions -> criterions
- foot -> foots -> foots
- loaf -> loafs -> loafs
- person -> people -> people
Ryan Bigg
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1Hm, that doesn't seem consistent to me. The plural of `people` is `peoples`, not `people`. Maybe they actually force it to have this property. – Niklas B. Feb 29 '12 at 19:37
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@NiklasB: The plural of person is people . There is no word as "Peoples". Brush up your English .. :) – Mithun Sasidharan Feb 29 '12 at 19:46
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@NiklasB. : Its can be argument. We back in India havent encountered Peoples yet !! – Mithun Sasidharan Feb 29 '12 at 19:54
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@Mithun: Hehe :P I somehow remembered that from some long-past English lesson. – Niklas B. Feb 29 '12 at 19:55
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The pluralize is particularly bad at things like non-count nouns. For example: advice, furniture, oxygen. The pluralizer adds an "s" to all of them. – Marc Talbot Feb 29 '12 at 21:31
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Nice set of examples here. I haven't been able to find a counterexample either. (Btw, it should be "analysis -> analyses -> analyses".) – hoffm Feb 29 '12 at 23:01
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In more recent versions of Rails, the counterexample from another answer no longer works, so you could add it to your list: taxi -> taxis -> taxis – hoffm Oct 19 '17 at 14:57