(K,V) Tarkoittaa siis Key ja Value, sehän on selvää.
Kokoan leikkeitä ohjeista:
http://www.dartlang.org/language-tour/#generics
Generics
If you look at the API documentation for the basic array type, List, you'll see that the type is actuallyList<E>. The <...> notation marks List as a generic (or parameterized) type—a type that can declare formal type parameters.
For example, if you intend for a list to contain only strings, you can declare it as List<String> (read that as "List of String").
....
Generic types can save you the trouble of creating all these interfaces. Instead, you can create a single interface that takes a type parameter:
interface Cache<T> { T getByKey(String key); setByKey(String key, T value); }
In this code, T is the stand-in type. It's a placeholder that you can think of as a type that a developer will define later.
Using collection literals
Both built-in collection types are parameterized: lists and maps. Parameterized literals are just like the literals you've already seen, except that you add <type> before the opening bracket. For example:
List<String> names = <String>['Seth', 'Kathy', 'Lars']; Map<String, String> pages = <String>{ // specify value type: String 'index.html':'Homepage', // (the key type is implicitly String) 'robots.txt':'Hints for web robots', 'humans.txt':'We are people, not machines' };
NO? Näyttää siltä siis, että <> merkinnän sisällä on "tyyppi"...
..
To specify one or more types when using a constructor, put the types in angle brackets (
<...>
..
Generic collections and the types they contain
Dart generic types are reified, which is a fancy way of saying that they carry their type information around at runtime. = = = = = = = = = = = = = = = = = = = = = = = = =
Collection<E>HashSet<E>Iterable<E>Iterator<E>List<E>Queue<E>Set<E>HashMap<K, V>LinkedHashMap<K, V>Map<K, V> mapping a key to a value.Completer<T>Future<T>
SIIS: E T K V What is this T in <T> ?
Interface Future<T>
A Future is used to obtain a value sometime in the future. Receivers of a Future obtain the value by passing a callback to then.
========================================================What is this E in <E> ?
===========================================
Typedefs can be parameterized.typedef int Compare<T>(T a, T b);
class SortedCollection<T> {
Compare<T> compare;
SortedCollection(this.compare);
}
main() {
SortedCollection<int> s = new SortedCollection<int>((a,b) => a - b);
print(s.compare is Compare<int>); // true
print(s.compare('a','b')); // checked mode throws exception
}typeParameter:
identifier (extends type)?
;
typeParameters:
`<' typeParameter (`,' typeParameter)* `>'
;
A type parameter T may be suffixed with an extends clause that specifies
the upper bound for T.
A type parameter T may be suffixed with an extends clause that specifies
the upper bound for T. ....
Tässäpä hieman sulattelemista... Täydennän tekstiä vielä...
http://c.dart-examples.com/learn/variables/collections
Tämä kirjoitus tuo hieman lisävalaistusta asiaan...
.
