Add "Spread operator"

[DartBot]

This issue was originally filed by guichard.ad...@gmail.com

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I did not find any informations about this operator during my Dart trip :

The spread operator allows to invoke an action on all items of an aggregate object. It is equivalent to calling the collect method like so:

(translated in Dart from Groovy exemple)
parent*.action; //equivalent to:
parent.forEach((child) { child?.action; });

or
List<Parent> parents;
[. . .]
List<String> parentNames = parents*.name

Groovy page discribing this operator:
http://groovy.codehaus.org/Operators

Thanks for your support,
Adrien

[anders-sandholm]

Removed Type-Defect label.
Added Type-Enhancement, Area-Language, Triaged labels.

[gbracha]

Set owner to @gbracha.
Added Accepted label.

[DartBot]

This comment was originally written by @kaendfinger

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This is very useful, I used to be a huge user of Groovy, so I know how it feels to use them. In future versions of the spec, this would a great addition!

[DartBot]

This comment was originally written by @seaneagan

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So:

  parents*.name

would be equivalent to:

  parents.map((parent) => parent == null ? null : parent.name);

I think more useful would be having a way of closurizing instance methods from a class instead of instance, then if issue #41 is fixed adding a "?" option to that, so something like:

  parents.map(Parent?.name)

  class Parent {
    String get name;
  }

[munificent]

Here's an updated link to the relevant Groovy feature: http://groovy-lang.org/operators.html#_spread_operator