Null propagation operator (?) and passing null values are failing

Hi,

(1) Getting an exception when trying to use null propagation operator: DynamicExpresso.Exceptions.ParseException Neither of the types ‘null’ and ‘Boolean’ converts to the other (at index 31). This is in line (2) on Parse stage.

(2) Getting an exception when passing a null value via parameter class (line 2). Need to specify a type name as a second parameter one more time to work it out. Basically when using a name/value Parameter constructor will throw an exception if provided value is null, the other constructor (name/type/value) won’t throw. This behaviour is unclear because parameter type was already provided on Parse stage and looks like it should be possible just to provide a null value.

class Scope {
    public bool Value { get; set; }
}

var interpreter = new Interpreter();

(1) var func = interpreter.Parse("Scope?.Value == true", new Parameter("Scope", typeof(Scope)));
(2) var result = func.Invoke(new Parameter("Scope", typeof(Scope), null));

[davideicardi]

@halamah Just released v2.9.2

[metoule]

For the second issue, it’s because the Parameter class is used to declare both parameters (for which the type is required) and arguments (for which the type can be inferred from the Parameter). If the object value is null, there’s no way to detect its type, which is why an ArgumentNullException is thrown.

Note that you can directly invoke the lambda with the arguments’ values, without the need of creating Parameter instances:

var interpreter = new Interpreter();
var func = interpreter.Parse("Scope?.Value == true", new Parameter("Scope", typeof(Scope)));
var result = func.Invoke(null);