public MessageExpression(IExpression target, string selector, IEnumerable<IExpression> arguments)
{
this.target = target;
this.selector = selector;
if (char.IsLetter(selector[0]))
this.isname = true;
if (selector[0] == '!' && selector.Length > 1 && char.IsLetter(selector[1]))
this.isname = true;
if (arguments == null)
this.arguments = new List<IExpression>();
else
this.arguments = arguments;
}