Question 78470 in Flutter Question posted in
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Required parameters per set flutter

let’s say I have a class that has a particular style and placement for 2 buttons. I need the style and placement of buttons to be the same across some aspects of the app. As a result a programmer can add a text and the onTap function of the primary button, and if UI contains a second button programmer can add that as well.

class ButtonPlacement extends StatelessWidget {
  const ButtonPlacement({required this.primaryButtonText,required this.primaryButtonOnTap,
   this.secondaryButtonText,this.secondaryButtonOnTap, super.key});
etc

My question is, is there a way to throw a compile error just like in null safety required, if programmer adds lets say a secondary text but not a secondary onTap function, as these two go together as you understand.

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3

Answers


  1. Chosen as BEST ANSWER
    0

    I just created a new class with these two variables, so programmer should input at most two of these classes instead of 4 variables. I will keep question open as I am intrigued to see other solutions

     class ButtonAttributes {
  String text;
  Function() onTap;

  ButtonAttributes({required this.text, required this.onTap});
}

  2. 0

    You can use assert which will only work in development.

    class ButtonPlacement extends StatelessWidget {
  final String primaryButtonText;
  final Function() primaryButtonOnTap;
  final String? secondaryButtonText;
  final Function()? secondaryButtonOnTap;
  const ButtonPlacement({
    required this.primaryButtonText,
    required this.primaryButtonOnTap,
    this.secondaryButtonText,
    this.secondaryButtonOnTap,
    super.key,
  }) : assert((secondaryButtonText == null && secondaryButtonOnTap == null) ||
            (secondaryButtonText != null && secondaryButtonOnTap != null));
}

    So if you try to create an instance of ButtonPlacement with one asserted parameter provided but not the other, it will throw and error in the console when you run it.

    ButtonPlacement(
  primaryButtonOnTap: () {},
  primaryButtonText: 'text',
  secondaryButtonText: '', // throws a Failed assertion error in the console
)
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  3. 0

    you can use ErrorWidget on debug mode and even better, Bug report on release if you want. you can even write your own message in way the other team will understand maybe native language.

    the simplest way is :

    class OurCompanyButton extends StatelessWidget {
  final String primaryButtonText;
  final Function() someFunction;
  const OurCompanyButton({Key? key, required this.primaryButtonText, required this.someFunction}) : super(key: key);

  @override
  Widget build(BuildContext context) {

    if(kDebugMode){

      String message = '';

      if(primaryButtonText.isEmpty){
        message = 'Yo, the label is empty, is not our standard';
        throw ErrorWidget(Exception(message));
      }

      if(someFunction.runtimeType is String){
        message = 'this fuction should return a void';
        throw ErrorWidget(Exception(message));
      }

    }
    
    if(kReleaseMode){
      return OurCompanyBugReportWidget();
    }

    return TextButton(onPressed: someFunction, child: Text(primaryButtonText));
  }

}

    in your case you can check :

    if(function1 != null && fuction2 == null){
        message = 'you only provide function1, please add fuction2 its nullable but its necessary';
        throw ErrorWidget(Exception(message));
      }
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