Defer Statement¶
Go’s defer statement schedules a function call to run when the enclosing function returns, regardless of which return statement was reached or whether a panic is in flight: defer file.Close() right after opening a file guarantees the close happens at every exit path, without needing a finally block. Multiple deferred calls run in last-in-first-out order, and they can still read and modify the function’s named return values before it actually returns.
Unlike a try/finally block, defer is not tied to a lexical block: it can be scattered anywhere in the function body, right next to the resource acquisition it cleans up, rather than requiring the rest of the function to be wrapped in a block.
PHP has no defer statement. Guaranteed cleanup on every exit path is expressed with try/finally, which does require wrapping the relevant code in a block, or with a destructor __destruct() that runs when the object holding the resource is garbage-collected, which is not guaranteed to happen at a predictable point in the function’s execution.
<?php
// No defer: cleanup must be wrapped, or moved into a destructor.
function readConfig(string $path): array {
$handle = fopen($path, 'r');
try {
return parse($handle);
} finally {
fclose($handle);
}
}
?>
See also Defer statement in the Go specification.
Related : Finally, Destructor, Exception
