Guava: Replace 'iff' by 'if' in docs.

[m-berling]

Just a minor issue, but many javadocs of the new common.graph package contain a specific typo, using the word (?) "iff" instead of "if" in conditional expressions, e.g. "Returns true iff graph has at least one cycle."
Maybe you like to fix this by a package-global search/replace?

[jonahgreenthal]

That's not a typo; it means "if and only if".

[m-berling]

Oops, sorry did not know this, being not a native English speaker.

Something learned again, thx!

[jbduncan]

But then again, it's not a word I've personally seen used in _any_ context apart from Guava and Spotless, and I'm a born Englishman. (Is it a word that originated in the US perhaps?)

We were never taught the term in our lectures at university, and I don't remember coming across it in any computer science literature I've read. We always used the phrase "if and only if" instead, so I thought "iff" was a typo too until I searched it up a few days ago. So I'm not surprised at all by @m-berling's confusion on this.

So I think it's worth replacing all occurrences of "iff" with "if and only if" in the javadocs, if only to make things explicit and clearer.

[Stephan202]

Maybe the term is more common in mathematics and logic. I'm not a native speaker and I thought it was actually quite well known.

Personally I like its brevity, but I recall seeing a PR to "fix" a similar typo in some other project a few months ago. So indeed, a case can be made that it's better to be explicit.

[m-berling]

Thanks for your comments, @jbduncan and @Stephan202! Yes, according to Wikipedia it is more common in logic, maths and philosophy, and I think it is quite useful there (iff you know this term).
AFAIK there is no similar abbreviation in German language, so I was not aware of it at all.

IMHO, in the current context of the graph package, the "iff" (or "if and only if") could easily be replaced by a simple "if" in most cases: "Returns true if graph has at least one cycle." Especially, this would conform to the common usage throughout the Guava API docs, e.g. Strings.isNullOrEmpty(): "Returns true if the given string is null or is the empty string."

Well, I'm just reopening this issue to let the people at guava decide... It is a very minor issue, anyway.

[kevinb9n]

Thanks for opening this. Our not-well-enforced policy has been to never use "iff" (or "e.g.", or "i.e.", or really most abbreviations) in our javadoc.

[jrtom]

This has been fixed per the above commit.