Description
Now when invalid token / expression is encountered during evaluation throw statement is used to notify user something went wrong. In scenarios where EE is "proxied" behind some interface (for example a simple web application where I can create and evaluate my scripts) this is suboptimal behavior.
throwis expensive and shouldn't be used in scenarios where can be triggered often- it makes hard for users of EE to customize onerror behavior, texts of errors and recover from errors (forces
try-catch) - there is no well defined list of recognized errors, users have to look them up in source code
This suggestion hence proposes that EE.ScriptEvaluate would return ExpressionEvaluatorResult insted of object. ExpressionEvaluatorResult is technically a tuple (could be reduced to a tuple) but for the sake of supporting pre-tuple versions of c# it would be nice to keep this as a class.
public class ExpressionEvaluatorResult {
public object Result {get; set;} // <-- this is what ScriptEvaluate returns now
public EvaluationResults State {get; set;} // <-- enum indicating result of evaluation
public EvaluationResultErrorInfo ErrorInfo {get; set;} // <-- when "ok" this is null
}Inner members definitions:
public enum EvaluationResults {
Ok, // <-- first entry indicates the evaluation was successful
MissingLParen, // <-- following entries all indicate an error
MissingRParen
...
}
public class EvaluationResultErrorInfo {
public int Line {get; set;} // <-- line in script where error occured
public int Character {get; set;} // <-- character index in that line
public string Message {get; set;} // <-- text we now pass to throw
}Usage would then be:
ExpressionEvaluatorResult result = new ExpressionEvaluator("return 1 + 1;");
if (result.State == EvaluationResults.Ok) {
// script evaluated successfully
int ret = (int)result.Result;
}Please note that all naming used is open for consideration and improvement, it should be as intuitive as possible and this is just from the top of my head.