Strings
Strings are immutable, which is a fancy way of saying that string operations create new strings instead of modifying existing strings. Strings (like numbers) are hashable, meaning that unique objects have unique hash codes to tell them apart. If we assign a variable to a variable holding a string, both will have the hash code because they are the same object.
| primitives/strings.dart | |
| | var str1 = "foo", |
| | str2 = str1; |
| | str1.hashCode; // 596015325 |
| | str2.hashCode; // 596015325 |
But if we modify the first string, the result will be an entirely new object while the copy continues to point to the original string.
| primitives/string_concat.dart | |
| | str1 = str1 + "bar"; |
| | |
| | str1.hashCode; // 961740263 |
| | str2.hashCode; // 596015325 |
Dart goes out of its way to make working with strings easy. It is possible to create multiline strings by enclosing them in triple quotes.
| primitives/strings_triple.dart | |
| | """Line #1 |
| | Line #2 |
| | Line #3"""; |
In addition to the + string concatenation operator, Dart considers adjacent strings to be concatenated.
| primitives/strings_adjacent.dart | |
| | 'foo' ' ' 'bar'; // 'foo bar' |
This adjacent string convenience even extends to multiline strings.
| primitives/strings_adjacent.dart | |
| | 'foo' |
| | ' ' |
| | 'bar'; // 'foo bar' |
Another convenience of Dart strings is the ability to interpolate variables and expressions into them. Dart uses $ to denote variables to be interpolated.
| primitives/strings_interpolation.dart | |
| | var name = "Bob"; |
| | |
| | "Howdy, $name"; // "Howdy, Bob" |
If there is potential for confusion over where the variable expression ends and the string begins, curly braces can be used with $.
| primitives/strings_interpolation.dart | |
| | var comic_book = new ComicBook("Sandman"); |
| | |
| | "The very excellent ${comic_book.title}!"; |
| | // "The very excellent Sandman!" |
Multiline strings and built-in expression interpolation are a huge win for the beleaguered JavaScripter. This effectively eliminates the need for a separate templating library. Templating is built in!