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avoid-default-tostring

v1.30.0
warning
effort: 4m
teams+

Warns when a class is the target of the toString() invocation, but does not implement toString.

The result of calling toString() on such classes is Instance of ... which is usually not expected.

Example​

❌ Bad:

void fn(SomeClass some) {
  // LINT: The class does not implement 'toString' and will give no meaningful output.
  //  Try implementing 'toString' or replacing with another value.
  some.toString();

  // LINT: The class does not implement 'toString' and will give no meaningful output.
  //  Try implementing 'toString' or replacing with another value.
  print('$some');

  // LINT: The class does not implement 'toString' and will give no meaningful output.
  //  Try implementing 'toString' or replacing with another value.
  [some].toString();
}

class SomeClass {}

✅ Good:

void fn(SomeClass some) {
  some.toString();
  print('$some');
}

class SomeClass {
  @override
  String toString() => 'hi';
}

Additional Resources​

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