(Visual FoxPro) 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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loChilkatGlob
LOCAL lnSuccess
LOCAL loMailman
LOCAL loTask
LOCAL lnMaxWaitMs
LOCAL lnNumMessages
LOCAL loEmail
LOCAL i

* All Chilkat classes can be unlocked at once at the beginning of a program
* by calling UnlockBundle.  It requires a Bundle unlock code.
loChilkatGlob = CreateObject('Chilkat_9_5_0.Global')
lnSuccess = loChilkatGlob.UnlockBundle("Anything for 30-day trial.")
IF (lnSuccess <> 1) THEN
    ? loChilkatGlob.LastErrorText
    RELEASE loChilkatGlob
    CANCEL
ENDIF

loMailman = CreateObject('Chilkat_9_5_0.MailMan')

* Set the POP3 server's hostname
loMailman.MailHost = "pop.someMailServer.com"

* Set the POP3 login/password and any other requirements..
loMailman.PopUsername = "myLogin"
loMailman.PopPassword = "myPassword"
loMailman.PopSsl = 1
loMailman.MailPort = 995

* Connect to the POP3 server:
loTask = loMailman.Pop3BeginSessionAsync()
IF (loMailman.LastMethodSuccess = 0) THEN
    ? loMailman.LastErrorText
    RELEASE loChilkatGlob
    RELEASE loMailman
    CANCEL
ENDIF

* Start the background task.
lnSuccess = loTask.Run()
IF (NOT lnSuccess) THEN
    ? loTask.LastErrorText
    RELEASE loTask
    RELEASE loChilkatGlob
    RELEASE loMailman
    CANCEL
ENDIF

* Wait for the POP3 connect task to finish.
* The 1/0 returned by Wait applies to the Wait method call, not the task.
lnMaxWaitMs = 30000
lnSuccess = loTask.Wait(lnMaxWaitMs)
IF (NOT lnSuccess OR (loTask.StatusInt <> 7) OR (loTask.TaskSuccess <> 1)) THEN
    IF (NOT lnSuccess) THEN
        * The task.LastErrorText applies to the Wait method call.
        ? loTask.LastErrorText
    ELSE
        * The ResultErrorText applies to the underlying task method call (i.e. the Pop3BeginSession)
        ? loTask.Status
        ? loTask.ResultErrorText
    ENDIF

    RELEASE loTask
    RELEASE loChilkatGlob
    RELEASE loMailman
    CANCEL
ENDIF

RELEASE loTask

* Get the number of messages in the mailbox.
loTask = loMailman.GetMailboxCountAsync()

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

lnSuccess = loTask.Run()
lnSuccess = loTask.Wait(lnMaxWaitMs)
lnNumMessages = loTask.GetResultInt()
RELEASE loTask
IF (lnNumMessages = 0) THEN
    RELEASE loChilkatGlob
    RELEASE loMailman
    CANCEL
ENDIF

loEmail = CreateObject('Chilkat_9_5_0.Email')

FOR i = 1 TO lnNumMessages

    loTask = loMailman.FetchByMsgnumAsync(i)
    IF (loMailman.LastMethodSuccess = 0) THEN
        ? loMailman.LastErrorText
        RELEASE loChilkatGlob
        RELEASE loMailman
        RELEASE loEmail
        CANCEL
    ENDIF

    lnSuccess = loTask.Run()
    lnSuccess = loTask.Wait(lnMaxWaitMs)
    IF (NOT lnSuccess OR (loTask.StatusInt <> 7) OR (loTask.TaskSuccess <> 1)) THEN
        IF (NOT lnSuccess) THEN
            * The task.LastErrorText applies to the Wait method call.
            ? loTask.LastErrorText
        ELSE
            * The ResultErrorText applies to the underlying task method call (i.e. the FetchByMsgnum)
            ? loTask.Status
            ? loTask.ResultErrorText
        ENDIF

        RELEASE loTask
        RELEASE loChilkatGlob
        RELEASE loMailman
        RELEASE loEmail
        CANCEL
    ENDIF

    * 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.  

    lnSuccess = loEmail.LoadTaskResult(loTask)
    RELEASE loTask

    IF (NOT lnSuccess) THEN
        ? loEmail.LastErrorText
        RELEASE loChilkatGlob
        RELEASE loMailman
        RELEASE loEmail
        CANCEL
    ELSE
        ? loEmail.From + ": " + loEmail.Subject + CHR(10)
    ENDIF

NEXT

RELEASE loChilkatGlob
RELEASE loMailman
RELEASE loEmail