TryExecute

// Usage:
// salesforce.TryExecute<string, QueryResult<Deal>, System.Exception>(
//     "select Id, Name from Deal__c",
//     (svc, qry) => { return svc.Query<Deal>(qry); },
//     (ex) => { System.Diagnostics.Trace.WriteLine(ex.Message); },
//     3);
public static TOut TryExecute<TIn, TOut, TException>(this ISalesforceService service, TIn arg, Func<ISalesforceService, TIn, TOut> executeHandler, Action<TException> errorHandler, int retryCount) where TException : System.Exception
{
    TOut result = default(TOut);

    try
    {
        result = executeHandler(service, arg);
    }
    catch (TException e)
    {
        if (retryCount == 0)
        {
            errorHandler(e);
        }

        service.TryExecute<TIn, TOut, TException>(arg, executeHandler, errorHandler, --retryCount);
    }

    return result;
}