VFP does not support callbacks. You can try file #28338 which adds such functionality.

>
>Can I use a pointer to the application function in VFP?
>
>I use bszip.dll to zip files. This .dll has a function zCompressFiles that has the following VBA syntax:
>
>

>Declare Function zCompressFiles Lib "bszip.dll" _
>      (ByVal TempDir As String, _
>       ByVal Password As String, _
>       ByVal CompressionMethod As Long, _
>       ByVal ResetArchiveAttribute As Byte, _
>       ByVal SpanSize As Long, _
>       ByVal Comment As String, _
>       ByVal RTInfoFunc As Long) As Long
>

>
>Description of the RTInfoFunc is as follows:
>
>

>RTInfoFunc- pointer to the application function, which will be called periodically (after 1 sec) from
>'          the library to show runtime information, for example some kind of progress bar.
>'          Within this function, application can call zGetRunTimeInfo or zCancelOperation.
>'          If nil, no runtime information will be available.
>'          In VB5+, this may be called by using AddressOf in the call, in VB4 set to nil.
>

>
>Can I use this in my VFP application to report on the progress of zip process?