Can lambda expressions only be used as conditional judgments and return bool?

To implement the mocked foreach, I use an extension method:

public static class Extend
{
     public static void All<T>(this IEnumerable<T> source, Action<T> action)
     {
         foreach (var item in source)
             action(item);
     }
}

I want to change the money field of each npc in List<Npc> NearNpcs to 10, so I wrote a Lambda string:

"NearNpcs.All(n=>n.money=10)"

(The InterpreterOptions.LambdaExpressions setting is already turned on, and the Extend class and associated required variables are registered.)

It reported the error:

DynamicExpresso.Exceptions.ParseException: A value of type ‘Int32’ cannot be converted to type ‘Boolean’ (at index 0).

Does Lambda parsing currently only support conditional parsing that can return bool?

[metoule]

I’ve reproduced with a simpler example that doesn’t require registering the extension method (using List.ForEach):

private class Npc
{
	public int Money { get; set; }
}

[Test]
public void Lambda_ShouldAllowActionLambda()
{
	var target = new Interpreter(InterpreterOptions.Default | InterpreterOptions.LambdaExpressions);
	target.EnableAssignment(AssignmentOperators.All);

	var list = new List<Npc>() { new Npc { Money = 10 } };
	target.SetVariable("list", list);

	var result = target.Eval(@"list.ForEach(n => n.Money = 5)");
	Assert.IsNull(result);
	Assert.AreEqual(5, list[0].Money);
}

Exception:

DynamicExpresso.Exceptions.NoApplicableMethodException : No applicable method ‘ForEach’ exists in type ‘List`1’ (at index 5).

[metoule]

Yes, that’s the issue I suspect: we probably find the ActionToAll method, but can’t use it because the lambda parser expects the lambda to have a return value. I’ll have a look, thanks for posting the code!