how can i access List. parameter from Method constructor in Flutter-CodePudding

Is it possible to get access from the constructor to a List dot Parameter?

What I want is one function instead of 2 or more something like this.

void somethingA() 
{ someList.where((item) => item.A == "123") }

void somethingB() 
{ someList.where((item) => item.B == "456") }

to something like this

void something(List list.XY) 
{ someList.where((item) => item.list.XY == "123") }

thanks for the help.

CodePudding user response：

if you want to get a list based on its items :

List<List> someList = [["a", "b"], ["c", "d"]];

  void something(List<List> list){
    list.where((element){
      return element == ["a", "b"];
    });
  }

based on its specific item :

List<List> somethingB(List<List> list){
    List<List> result = [];
    list.where((element){
      element.map((e){
        if(e == "a"){
          result.add(e);
        }
        if(e == "b"){
          result.add(e);
        }
      }).toList();
    });
    return result;
  }

CodePudding user response：

You cannot reall pass something like list.XY, but you can come close:

Iterable<T> itemsWithValue5<T>(Iterable<T> values, int Function(T) selector) {
  return values.where((value) => selector(value) == 5);
}

void main() {

  const words = ['Hello', 'World'];
  
  final wordsWithLength5 = itemsWithValue5<String>(words, (word) => word.length);
  
  print(wordsWithLength5);
}

The selector parameter takes a function that gets an item (in this case of type string) and transforms it into something else, in this case an int. This allows you to write something like (word) => word.length as your selector, which is alreasy pretty close to list.XY.