Is String # pluralizing idempotent?

Question

That is, for any string string , the following is true:

 string.pluralize == string.pluralize.pluralize 

Answer 1

pluralize is NOT Idempotent. I can prove this with an example (courtesy of a personal Facebook post that hit some geeks of the language).

 "taxi".pluralize => "taxis" "taxis".pluralize => "taxes" "taxi".pluralize.pluralize => "taxes" 

So, “taxi” (what leads you) to “taxi” (arrangement or order) to “taxes” (proper pluralization of “taxi”). I am sure there are other examples, but they are certainly difficult to find.

Despite evaluating or accepting this answer, but I couldn’t exactly put it in the commentary on the Ryan post.

Answer 2

I can not think of a case when this is not so.

I just tried the following words and did not change after the second pluralization. However, some of them “break down” in interesting ways due to two reasons: 1) Rails pluralization rules are actually pretty stupid and 2) English is tough .

• analysis → analyzes → analysis
• media → media → media
• news → news → news
• cactii → cactiis → cactiis
• criterion → criteria → criteria
• foot → foots → foots
• loaf → loafs → loafs
• people → people → people