Conditionals inside nested expressions

[mit-mit]

Flutter code contains UI descriptions that are naturally ordered, with a set of arguments typically specified in the rough order they appear on the screen, e.g.:

  Widget buildBody() {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Text('Text 1'),
        Text('Text 2'),
        Text('Text 3'),
      ],
    );
  }

However, when some of these elements need to be conditionally shown, the developer is forced to restructure the method "backwards"; with the conditional code first, and then the code for what surrounds the conditional code:

  Widget buildBody() {
    List<Widget> children;
    children.add(Text('Text 1'));
    if (someCondition == true) {
      children.add(Text('Text 2'));
    }
    children.add(Text('Text 3'));

    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: children,
    );
  }

The present issue requests support for some way of writing conditional code "as part of the statements".

[mdebbar]

@mit-mit you might find the ui-as-code project interesting. It covers several issues like this one. See https://github.com/munificent/ui-as-code/blob/master/Motivation.md#p1-conditionally-omitting-content.

cc @munificent

[mit-mit]

Yes, I'm very aware of that effort. This issue more formally tracks one of the parts from it.

[munificent]

Do we need both this issue and #62? They seem like duplicates.

[munificent]

I guess we can close this now that we have collection-if. :)