Calling a method by name with parameters (or build like sql)

Question

.Net Version 4.5.1

 

Very Brief Background

I have a console application where the user enters a function and parameters. Rather than adding supported functions to a dictionary of some kind, I'd like to just have it call the method by name, using the method signature to validate the parameters. I can gather all the information I need in theory, but can't figure out how to CALL the expression.

 

I think I know why--it's because I can't figure out how to coerce my parameters into a form the Expression.Call line will accept. I tried using the ParameterExpression class, but it doesn't seem to contain the values, only the types and names.

 

What I Want to Do 

/// <summary>
/// Call a method in this class instance by name and parameters
/// </summary>
/// <param name="methodName"></param>
/// <param name="args"></param>
/// <returns></returns>
public void Execute(string methodName, object[] args)
{
    //get method we will be calling
    MethodInfo method = GetMethodByName(methodName);

    //validate & retrieve parameters based on the method signature
    object[] parameters;
    if (!GetAndValidateParams(
                method.GetParameters().Select(pd => pd.ParameterType).ToArray(),
                args,
                out parameters))
        return; //exit on failed validation of parameters

    //call method using signature -- this is where I'm getting an error
    Expression.Call(method, parameters);
}

 I would also be happy with the ability to "assemble" a method call, like in this pseudocode:

MethodCall mc = new MethodCall(methodInfo);
mc.ClassInstance = this;
mc.Parameters.AddRange(parameters);
mc.Execute();

Thank you in advance for any help or guidance you can provide!

 

Daniel

 

Just in Case: The Validation Method

//validates that types are as expected. Only accepts string, int and decimal
private bool GetAndValidateParams(Type[] expected, object[] args, out object[] convertedArgs)
{
    Console.Write("Validating parameters...");

    //check for any unsupported types
    convertedArgs = null;
    Type[] supportedTypes = new Type[] { typeof(decimal), typeof(string), typeof(int) };
    if (expected.Any(t => !supportedTypes.Any(st => t == st))) return false;

    if (expected == null) return false;
    if (expected.Count() == 0 && (args == null || args.Count() == 0))
    {
        Console.Write("Success.\r\n");
        return true;
    }
    convertedArgs = new object[args.Count()];
    for (int x = 0; x < expected.Count(); x++)
    {
        //check to make sure there are args left
        if (x > (args.Count() - 1)) return false;

        //if we have an arg and an expectation, check them
        try { convertedArgs[x] = Convert.ChangeType(args[x], expected[x]); }
        catch {return false;}
    }

    //If we got here, everything was validated successfully
    Console.Write("Success.\r\n");
    return true;
}