Attributes in Dart

Question

Are there any plans to introduce attributes
for classes, methods, parameters of methods,
something like C# or Java attributes ?

    [Test]
    class SomeClass
    {
        [Test]
        someMethod()
    }

or

    @Test
    class SomeClass
    {
        @Test
        someMethod(@Test int param)
    }

For many frameworks it would be very useful

Answer 1

In dart, they are called metadata / annotation. The syntax is quite close to java. Here's a example :

@Test testMethod() {}

In Dart Specification you can read :

Metadata consists of a series of annotations, each of which begin with the character @, followed a constant expression that starts with an identifier. It is a compile time error if the expression is not one of the following:

• A reference to a compile-time constant variable.
• A call to a constant constructor.

[....]

Metadata can appear before a library, class, typedef, type parameter, constructor, factory, function, field, parameter, or variable declaration and before an import or export directive.

There're already some annotations predifined in dart:core. Particulary @override, @deprecated and @proxy.

Answer 2

Dart already has annotations, similar to Java in some ways, they're just not used in very many places yet, and they're not accessible from reflection yet either.

See this article: http://news.dartlang.org/2012/06/proposal-to-add-metadata-to-dart.html

Answer 3

Here's a brief introduction to the two metadata annotations currently available in the Dart meta library:

Dart Metadata is your friend.

This doesn't preclude you from using your own, but these are the two that have tooling integration with the Dart Editor.