strings: clarify usage of Title and ToTitle

This is intended to help clear up confusion around the usage of the
Title and ToTitle functions. It includes a link to define title case
to distinguish it from upper case. It also includes an additional
example for the ToTitle function to showcase the difference in behavior
between it and the Title function.

Fixes #33302

Change-Id: I44e62962fb04d0d22966a39eda3a2d16de7a2291
Reviewed-on: https://go-review.googlesource.com/c/go/+/187825
Reviewed-by: Rob Pike <r@golang.org>

diff --git a/src/strings/example_test.go b/src/strings/example_test.go
index 4f3a1ce8c6fdf869eb20b383d6a8ab98102a62b4..375f9cac6502e89a0124315a04c1700b8cbd13ae 100644 (file)
--- a/src/strings/example_test.go
+++ b/src/strings/example_test.go
@@ -247,14 +247,23 @@ func ExampleSplitAfterN() {
 }
 
 func ExampleTitle() {
+       // Compare this example to the ToTitle example.
        fmt.Println(strings.Title("her royal highness"))
-       // Output: Her Royal Highness
+       fmt.Println(strings.Title("loud noises"))
+       fmt.Println(strings.Title("хлеб"))
+       // Output:
+       // Her Royal Highness
+       // Loud Noises
+       // Хлеб
 }
 
 func ExampleToTitle() {
+       // Compare this example to the Title example.
+       fmt.Println(strings.ToTitle("her royal highness"))
        fmt.Println(strings.ToTitle("loud noises"))
        fmt.Println(strings.ToTitle("хлеб"))
        // Output:
+       // HER ROYAL HIGHNESS
        // LOUD NOISES
        // ХЛЕБ
 }

diff --git a/src/strings/strings.go b/src/strings/strings.go
index 73374813809192d0a1f9df7e4b70cec4ed8e5a74..cee315ce9e4027b9647a0b1f550f91b3b92c277a 100644 (file)
--- a/src/strings/strings.go
+++ b/src/strings/strings.go
@@ -610,7 +610,8 @@ func ToLower(s string) string {
        return Map(unicode.ToLower, s)
 }
 
-// ToTitle returns a copy of the string s with all Unicode letters mapped to their title case.
+// ToTitle returns a copy of the string s with all Unicode letters mapped to
+// their Unicode title case.
 func ToTitle(s string) string { return Map(unicode.ToTitle, s) }
 
 // ToUpperSpecial returns a copy of the string s with all Unicode letters mapped to their
@@ -626,7 +627,7 @@ func ToLowerSpecial(c unicode.SpecialCase, s string) string {
 }
 
 // ToTitleSpecial returns a copy of the string s with all Unicode letters mapped to their
-// title case, giving priority to the special casing rules.
+// Unicode title case, giving priority to the special casing rules.
 func ToTitleSpecial(c unicode.SpecialCase, s string) string {
        return Map(c.ToTitle, s)
 }
@@ -707,7 +708,7 @@ func isSeparator(r rune) bool {
 }
 
 // Title returns a copy of the string s with all Unicode letters that begin words
-// mapped to their title case.
+// mapped to their Unicode title case.
 //
 // BUG(rsc): The rule Title uses for word boundaries does not handle Unicode punctuation properly.
 func Title(s string) string {