[Bug]: Strange error when setting feature

[nschneid]

Is there already an issue for this?

• I have searched the existing issues

Current Behavior

rule r5 { % keep them lovely kebabs coming: leave det(kebabs, them) but mark "them" as Style=Vrnc
    pattern {
      X[lemma=they]; 
      Y-[det]->X;
    }
    commands { 
      X.Style="Vrnc";
    }
}

The above rule should apply to 1 token in my data. The pattern works but the command causes an error

GREW-ERROR : [line: 1] More than 10000 rewriting steps: check for loops or increase max_rules value. Last rules are: […r5, r5, r5, r5, r5, r5, r5, r5, r5, r5]

Setting the lemma is not a problem. The "Style" feature is listed in the project settings with "Vrnc" as a possible value, so I'm not sure what's wrong here.

Steps To Reproduce

1. Run the above rule on English-EWT test set
2. Error occurs

Project name

No response

Anything else?

No response

What browsers are you seeing the problem on?

Firefox

[bguil]

This is a well-know issue with rewriting. As a rule may apply several times in different parts of the same sentence, the system applies the rules iteratively until no more application is possible.

With your rule, after the first application, the pattern is still "there" and so the rule can apply again and again (with no effect).
In your case, you have to ensure that this cannot happen. The easiest way is to use a withoutcondition:

rule r5 { % keep them lovely kebabs coming: leave det(kebabs, them) but mark "them" as Style=Vrnc
    pattern {
      X[lemma=they]; 
      Y-[det]->X;
    }
    without { X.Style = "Vrnc" }
    commands { 
      X.Style="Vrnc";
    }
}

[nschneid]

Interesting! Could the error message be made more informative, e.g. "Note that a rule will apply continually as long as its precondition remains true"?