Instantiation of abstract class

[Anderson Aroeira Araujo]

Hi,

How do I do a instantiation of an a abstract class or interface?

Eg:

Java

interface Callback<T> {

  void execute(T arg0);

}

Callback<String> cs = new Callback<String>() {

  void execute(String arg0) {

   ;

  }

}

Dart

abstract class Callback<T> {

  abstract void execute(T arg0);

}

or

interface Callback<T> {

  void execute(T arg0);

}

If I do:

var callback = new Callback<String>() {

  void execute(String arg0) {

   ;

  }

}

I get the markers in the Dart Editor: Instantiation of a abstract class or New expression does not resolve to a constructor

There is a better approach to this? 

Which is the Dart way?

Thanks in advance.

[Ladislav Thon]

How do I do a instantiation of an a abstract class or interface?

You don't. There are no anonymous classes/object literals in Dart. See also http://dartbug.com/1089.

LT

[Matthew Butler]

Exactly. You must Extend the abstract class into a concrete class, or implement the implicit interface of the abstract class in a concrete class.

Matt

[Anderson Aroeira Araujo]

Thank you, guys. I'll wait then :-)

[Josh Gargus]

In Dart, you don't need this shortcut syntax for creating anonymous callback subclasses.  Instead, just pass a closure:

doSomethingAsynchronously(arg1, 

(result) => print('the operation completed successfully with result: $result) )

Cheers,

Josh

[Josh Gargus]

Grrr... I really need to figure out which Gmail shortcut I'm hitting to send prematurely...

doSomethingAsynchronous(arg1, arg2, (result) => print('completed with result: $result));

Cheers,
Josh

[Matthew Butler]

On Wednesday, July 18, 2012 3:14:42 PM UTC-3, Anderson Aroeira Araujo wrote:

Thank you, guys. I'll wait then :-)

Please notice that the bug is closed as 'wontfix'. This feature will not be coming to Dart in the foreseeable future. 

Here is a discussion which provides a little additional information on the recommended alternative to anonymous classes.
https://groups.google.com/a/dartlang.org/forum/#!topic/misc/rUWJMuDfJWc

Matt