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Returns a variable from shared memory
(PHP 4, PHP 5)
Code Examples / Notes » shm_get_var06-may-2005 10:01
You will still receive a notice use @: if(!defined(@shm_get_var($mutex, $mutex_key))) { shm_put_var($mutex, $mutex_key, 0); } jm
To follow up on the posts by anonymous, Bob Van Zant and chris at free-source dot com below (or, as must people inexplicably write, above) regarding the PHP warning and FALSE that shm_get_var returns if the variable key doesn't exist: My tests (with PHP4.3.4) show that defined() is useless here. Because the function defined(string) checks whether the constant whose name is string exists, the code <?php if ( defined(@shm_get_var($mutex, $mutex_key)) { ... } ?> acts the same ("..." does not get executed) whether the variable is defined or not--unless $mutex_key happens to identify a valid string that happens to be the name of a constant. :) Rather, <?php if ( @shm_get_var($mutex, $mutex_key) === FALSE ) { ... } ?> works, provided the object that was stored isn't actually FALSE (via <?php shm_put_var($mutex, $mutex_key, FALSE); ?>) It would be nice to have a completely air-tight solution, though. D'oh! bob van zant
This seems to work fine to detect the lack of presence of a key in shared memory and then init it to 0 when found: if(!defined(shm_get_var($mutex, $mutex_key))) { shm_put_var($mutex, $mutex_key, 0); } chris
if the variable_key asked for does not exist php generates a warning and shm_get_var() will return bool(false). there doesn't seem to be a clean way to test if a key exists.
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