I need some clarification on some code samples

Question

http://radar.oreilly.com/2013/05/dart-is-not-the-language-you-think-it-is.html

at the risk of asking a stupid question:

I have never seen this syntax before:

// Dart
class Point {
  num x, y;
  Point(this.x, this.y);

  String toString() =&gt; 'X: $x, Y: $y';
}

is &gt indicating a reference?

import 'dart:mirrors';

class LoggingProxy {
  InstanceMirror mirror;
  LoggingProxy(delegate)
    : mirror = reflect(delegate);

  noSuchMethod(Invocation invocation) {
    var name = invocation.memberName;
    print('${name} was called');
    return mirror.delegate(invocation);
  }
}

and what is the colon in:

LoggingProxy(delegate)
  : mirror = reflect(delegate);

doing?

score 1 · Accepted Answer · edited May 23 '17 at 11:57

1

The source code has been escaped for some reason:

String toString() =&gt; 'X: $x, Y: $y';

What do entities: < and > stand for?

It's simply => syntax shorthand for the function body that is equal to {return 'X: $x, Y: $y'; }
Should be String toString() => 'X: $x, Y: $y'; instead.

And this is constructor's initializer list:

LoggingProxy(delegate)
  : mirror = reflect(delegate);

edited May 23 '17 at 11:57

Community

1
1

answered Aug 08 '14 at 20:13

JAre

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#1 derp #2 ahh kinda the same thing but for a constructor? – chrisgotter Aug 09 '14 at 01:19
@chrisgotter #2 for example, final fields cannot be initialized in the constructor's body. But, if they depends on constructor's arguments, you can use initializer list. – JAre Aug 09 '14 at 01:34

I need some clarification on some code samples

1 Answers1