(.NET Core C#) Async Methods Returning an Object

Demonstrates how to call an asynchronous method that returns an object. This example reads email from a POP3 server using the Async versions of the Chilkat methods.

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// All Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
Chilkat.Global chilkatGlob = new Chilkat.Global();
bool success = chilkatGlob.UnlockBundle("Anything for 30-day trial.");
if (success != true) {
    Debug.WriteLine(chilkatGlob.LastErrorText);
    return;
}

Chilkat.MailMan mailman = new Chilkat.MailMan();

// Set the POP3 server's hostname
mailman.MailHost = "pop.someMailServer.com";

// Set the POP3 login/password and any other requirements..
mailman.PopUsername = "myLogin";
mailman.PopPassword = "myPassword";
mailman.PopSsl = true;
mailman.MailPort = 995;

// Connect to the POP3 server:
Chilkat.Task task = mailman.Pop3BeginSessionAsync();
if (mailman.LastMethodSuccess == false) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// Start the background task.
success = task.Run();
if (!success) {
    Debug.WriteLine(task.LastErrorText);

    return;
}

// Wait for the POP3 connect task to finish.
// The true/false returned by Wait applies to the Wait method call, not the task.
int maxWaitMs = 30000;
success = task.Wait(maxWaitMs);
if (!success || (task.StatusInt != 7) || (task.TaskSuccess != true)) {
    if (!success) {
        // The task.LastErrorText applies to the Wait method call.
        Debug.WriteLine(task.LastErrorText);
    }
    else {
        // The ResultErrorText applies to the underlying task method call (i.e. the Pop3BeginSession)
        Debug.WriteLine(task.Status);
        Debug.WriteLine(task.ResultErrorText);
    }

    return;
}

// Get the number of messages in the mailbox.
task = mailman.GetMailboxCountAsync();

// To keep the example short, we'll skip handling failures.
// The failures would be handled in the same way as shown above.

success = task.Run();
success = task.Wait(maxWaitMs);
int numMessages = task.GetResultInt();

if (numMessages == 0) {
    return;
}

Chilkat.Email email = new Chilkat.Email();

int i;
for (i = 1; i <= numMessages; i++) {

    task = mailman.FetchByMsgnumAsync(i);
    if (mailman.LastMethodSuccess == false) {
        Debug.WriteLine(mailman.LastErrorText);
        return;
    }

    success = task.Run();
    success = task.Wait(maxWaitMs);
    if (!success || (task.StatusInt != 7) || (task.TaskSuccess != true)) {
        if (!success) {
            // The task.LastErrorText applies to the Wait method call.
            Debug.WriteLine(task.LastErrorText);
        }
        else {
            // The ResultErrorText applies to the underlying task method call (i.e. the FetchByMsgnum)
            Debug.WriteLine(task.Status);
            Debug.WriteLine(task.ResultErrorText);
        }

        return;
    }

    // Each Chilkat object that can be a return value of an asynchronous task will
    // have a method named LoadTaskResult.  The object returned in the underlying
    // asynchronous method call is retrieved by calling LoadTaskResult. 

    // To say it another way: The application will provide a pre-existing object of
    // the desired return type (in this case it is an email object).  This object is
    // loaded by calling LoadTaskResult.  

    success = email.LoadTaskResult(task);

    if (!success) {
        Debug.WriteLine(email.LastErrorText);
        return;
    }
    else {
        Debug.WriteLine(email.From + ": " + email.Subject + "\n");
    }

}