Compile time error on incomplete interfaces

[Cogman]

class Test

{

  final int _x;

  final int _y;

  

  int get x => _x + 7;

  int get y => 8;

  

  Test.forThing(this._x, this._y);

}

abstract class Tester

{

  int get y;

}

class Jim implements Test, Tester

{

  int get x => 7;

  Jim();

}

void main() {

  Test bob = new Test.forThing(1, 2);

  Test jim = new Jim();

  print(jim.y);

}

Lets say we have the above code.

Now, I can understand not forcing Jim to implement all methods of Test (after all, it may only use 1 or 2 of those methods.) However, it looks like the fact that jim calls the y getter should have immediately thrown a compile time error since Jim doesn't implement a y getter.

Does that sound too crazy?  I just prefer the compile time errors to runtime errors.  I don't know how complex it would be to check that, but I think it might be worth it.

[Alan Knight]

The editor used to report unimplemented abstract methods from superclasses. I presume that it's one of the things that hasn't yet been turned on with the new analyzer, but should be soon.

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[Kasper Lund]

As far as I know this warning is almost ready to turned on again. Jaime knows the details!

Cheers,
Kasper

[Jaime Wren]

It was not trivial to check for all cases specified by the Language Spec, but fortunately we started work on this a little while ago:

Committed this morning with https://codereview.chromium.org/15500002/ (svn version 22949), "Jim" now has a warning.

In cases where there is a single missing override the name of the method/member is in the error code; in cases where there are multiple missing members "missing inherited members" is the error code.  When priorities allow, we'll put a quick fix on the error code to auto-insert the missing methods/getters/setters to resolve the warning.  I expect this to be especially helpful when your interface(s) have many members to override.

- Jaime

Jaime Wren |

Software Engineer |

jw...@google.com |

503.877.9736