4D Doc Center : Test semaphore

4D v13.4

Test semaphore


Test semaphore ( semaphore ) -> Function result

Parameter	Type	Description
semaphore	String	Name of the semaphore to test
Function result	Boolean	True = the semaphore exists, False = the semaphore doesn’t exist

Description

The Test semaphore command tests for the existence of a semaphore.

The difference between the Semaphore function and the Test semaphore function is that Test semaphore doesn’t create the semaphore if it doesn’t exist. If the semaphore exists, the function returns True. Otherwise, it returns False.

Example

The following example allows you to know the state of a process (in our case, while modifying the code) without modifying semaphore:

 $Win:=Open window(x1;x2;y1;y2;-Palette window)

 Repeat

    If(Test semaphore("Encrypting code"))

       POSITION MESSAGE($x3;$y3)

       MESSAGE("Encrypting code being modified.")

    Else

       POSITION MESSAGE($x3;$y3)

       MESSAGE("Modification of the encrypting code authorized.")

    End if

 Until(StopInfo)

 CLOSE WINDOW