I have some simple code like this:

enum myEnum {
      foo,
      bar,
      baz
}
    
mixin myMixin {

  final Map<myEnum, double> values = {
    myEnum.foo: 0.3,

    myEnum.bar: 5.2,

    myEnum.ter: 91.3,
  };

  double getValue(myEnum key, { double a = 0.0, double b = 0.0 }) {
    final double tot = a   b;
    double c = 0.0;

    switch(key) {
      case myEnum.foo | myEnum.bar:
        -1;
        break;
    }

    return values[key]!;
  }
}

and it is generating this error:

In constant expressions, operands of this operator must be of type 'bool' or 'int'.

in the line case myEnum.foo | myEnum.bar: but I cannot get the reason for it.

Any idea?

CodePudding user response：

You're not writing correct Dart. The way to match two different values in a switch is to have two case clauses:

case myEnum.foo:
case myEnum.bar:
  ...

The | operator is not defined on enums (usually, with enhanced enums you can declare one, it's a user-definable operator), and since the expression after case must be a constant expression, and | in constant expressions is only allowed for integers (bitwise or) and Booleans (Boolean or), the expression myEnum.foo | myEnum.bar is invalid in a number of ways:

• It's not constant.
• myEnum doesn't have a | operator.

You only got one of the errors.