Question

I found a chunk of code that I haven’t seen before:

declare(ticks = 1);
pcntl_signal(SIGINT, array($this, "catchSignal"));
pcntl_signal(SIGTERM, array($this, "catchSignal"));

I looked up the function in the PHP documentation, but I still don’t understand what this is used for. Please help me understand what this is used for and some examples of where this should be implemented.

Answer 1

The declare statement states to check for events every “tick”. A “tick” being roughly equal to a line of code. This is used in command line PHP scripts so you can catch interrupts and shutdown the script gracefully instead of just killing it.

The array($this, "catchSignal") in the pcntl_signal function is an odd work around (in my opinion) to support “objects” as parameters. Normally you would just do $this->catchSignal(), but PHP doesn’t accept class objects as parameters in this case. Thus the “array” syntax.

Basically, if the script is issued an Interrupt or Termination signal, call the $this->catchSignal() function before shutting down.