strings: fix Title function

[GwynethLlewelyn]

First of all: no, this is not #6801!

Instead, I just wanted to point out that the current strings.Title() implementation is a 'quick & dirty' way of dealing with titles; it does not respect proper English rules for title naming (although it might be appropriate for some languages, I don't know).

A suggestion was made on the Go Cookbook to implement it thusly:

func properTitle(input string) string {
	words := strings.Fields(input)
	smallwords := " a an on the to "

	for index, word := range words {
		if strings.Contains(smallwords, " "+word+" ") {
			words[index] = word
		} else {
			words[index] = strings.Title(word)
		}
	}
	return strings.Join(words, " ")
}

This is a clever and neat trick, and could be used for other languages as well (ex. in Portuguese the smallwords would have to include " de do da dos das " but possibly exclude "a" since that is by coincidence also a definite article, etc.).
The authors of the Go Cookbook did not seem to add a suggestion here, so I'm doing it 🙂

[ianlancetaylor]

Can you give an example of an input that would change under your proposal?

CC @mpvl

[GwynethLlewelyn]

Sure, the best example is on the Go Cookbook itself:

strings.Title("welcome to the dollhouse!") gives Welcome To The Dollhouse!

while

properTitle("welcome to the dollhouse!") gives Welcome to the Dollhouse!

which is grammatically correct (while the result from strings.Title() is not)

[bep]

As I suspect changing the existing strings.Title would be a hard sell, I wanted to point to a great third-party Go lib with both AP style and Chicago style titles:

https://godoc.org/github.com/jdkato/prose/transform

[ianlancetaylor]

Ah, I understand now. No, I don't think we can or should change strings.Title in that way. strings.Title acts as documented. Changing it would make it a different function, and would break backward compatibility. I agree that the sort of function you describe is useful, but it's not strings.Title. Also the function you describe is language-specific, and there are no such functions in the strings package.

Closing.

[GwynethLlewelyn]

I agree that strings.Title works exactly as described, it's just that the name of the function that is misleading! On the other hand, you're totally right that this is language-specific, and none of the other functions in strings have such a limitation (one thing is handling with runes — which are language-specific but easy to handle — the other thing is handling with grammar, so I get your point!).
Aye, there are plenty of ways of doing it 'the right way' and while I hadn't come across the prose series of packages, implementing 'proper' title capitalisation is not exactly rocket science. Also, I now understand that 'Title Case' (which is what strings.Title implements...) may mean something significantly different in the software development environment compared to the grammatical definition. So I should have done my research before making a suggestion here! Sorry about that.