POST OUTSIDE CALL
POST OUTSIDE CALL ( process )
| Parameter | Type | Description | |
|---|---|---|---|
| process | Integer | → | Process number |
This command is not thread-safe, it cannot be used in preemptive code.
Compatibility Note
This command was named CALL PROCESS in previous 4D releases.
Description
POST OUTSIDE CALL calls the form displayed in the frontmost window of process.
Important: POST OUTSIDE CALL only works between processes running on the same machine.
If you call a process that does not exist, nothing happens.
If process (the target process) is not currently displaying a form, nothing happens. The form displayed in the target process receives an On Outside Call event. This event must be enabled for that form in the Design environment Form Properties window, and you must manage the event in the form method. If the event is not enabled or if it is not managed in the form method, nothing happens.
Note: The On Outside Call event modifies the entry context of the receiving input form. In particular, if a field was being edited, the On Data Change event is generated.
The caller process (the process from which POST OUTSIDE CALL is executed) does not “wait”— POST OUTSIDE CALL has an immediate effect. If necessary, you must write a waiting loop for a reply from the called process, using interprocess variables or using process variables (reserved for this purpose) that you can read and write between the two processes (using GET PROCESS VARIABLE and SET PROCESS VARIABLE).
To communicate between processes that do not display forms, use the GET PROCESS VARIABLE and SET PROCESS VARIABLE commands.
Tip: POST OUTSIDE CALL accepts the alternate syntax POST OUTSIDE CALL(-1). In order not to slow down the execution of methods, 4D does not redraw interprocess variables each time they are modified. If you pass -1 instead of a process reference number in the process parameter, 4D does not post any outside call. Instead, it redraws all the interprocess variables currently displayed in all windows of any process running on the same machine.
Example
See example for Semaphore.