4D v13.4

Test semaphore

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4D v13.4
Test semaphore

Test semaphore 


 

Test semaphore ( semaphore ) -> Function result 
Parameter Type   Description
semaphore  String in Name of the semaphore to test
Function result  Boolean in True = the semaphore exists, False = the semaphore doesn’t exist

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

 
PROPERTIES 

Product: 4D
Theme: Process (Communications)
Number: 652

 
INDEX

Alphabetical list of commands

 
HISTORY 

Created: 4D v6.5

 
SEE ALSO 

Semaphore