CODEWITHSUNDEEP
dartflutter
Anderson Oki
Anderson Oki

Reputation: 657

C# Yield Return on Dart / Flutter Return List<String> in Loop

I have the following method:

List<DropdownMenuItem<String>> _buildGitIgnoreTemplateItems() {
    var _dropDownMenuItems = List<DropdownMenuItem<String>>();

    _gitIgnoreTemplateNames.forEach((templateName) {
        _dropDownMenuItems.add(DropdownMenuItem(
            child: Text(templateName),
            value: templateName,
        ));
    });

    return _dropDownMenuItems;
}

What i am trying to achived is remove the variable _dropDownMenuItems something like:

List<DropdownMenuItem<String>> _buildGitIgnoreTemplateItems() {
    _gitIgnoreTemplateNames.forEach((templateName) {
        **yield return** DropdownMenuItem(
            child: Text(templateName),
            value: templateName,
        );
    });
}

You can see similar implementation in other languages like: C#

Upvotes: 1

Views: 1106

Answers (3)

G&#252;nter Z&#246;chbauer
G&#252;nter Z&#246;chbauer

Reputation: 657118

C# is way too long ago, but it looks like Synchronous generators

Iterable<DropdownMenuItem<String>> _buildGitIgnoreTemplateItems() sync* {
    for(var templateName in _gitIgnoreTemplateNames) {
        yield DropdownMenuItem(
            child: Text(templateName),
            value: templateName,
        );
    }
}

but perhaps you just want

_gitIgnoreTemplateNames.map((templateName) => 
    DropdownMenuItem(
      child Text(templateName), 
      value: templateName)
    ).toList()

Upvotes: 2

Richard Heap
Richard Heap

Reputation: 51682

Dart has a simpler syntax to achieve what you want:

List<DropdownMenuItem<String>> _buildGitIgnoreTemplateItems() {
  return _gitIgnoreTemplateNames
      .map((g) => DropdownMenuItem(
            child: Text(g),
            value: g,
          ))
      .toList();
}

Upvotes: 1

R&#233;mi Rousselet
R&#233;mi Rousselet

Reputation: 276911

The equivalent in dart is with Stream and StreamController for async. And Iterable for sync. You can create them manually or using custom function with async* or sync* keywords

Iterable<String> foo() sync* {
  yield "Hello";
}


Stream<String> foo() async* {
  yield "Hello";
}

Upvotes: 1

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