November 20, 2008
Operator precedence gets me every time!
While working on a module last night, I couldn't figure out why I couldn't get caching to work. I have done object caching at least a dozen times before but I couldn't figure out why I was not able to get the cached object back. Here's the code I was using:
<?php
if($cache = cache_get($cid, 'cache') && $cache->data) {
dsm('Cached!');
return $cache->data;
}
?>I finally realized that cache_get() was indeed returning a cache object, but the code inside the if statement was never executing.
Then I saw my mistake. The && operator has a higher precedence that the = (assignment) operator, so the above statement is similar to this:
<?php
if($cache = (cache_get($cid, 'cache') && $cache->data)) {
...
}
?>So the solution is simply to wrap the assignment in parenthesis like so:
<?php
if(($cache = cache_get($cid, 'cache')) && $cache->data) {
dsm('Cached!');
return $cache->data;
}
?>
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