可以將 PHP Closure 指派給函式指標類型的原生變數，或將其作為函式引數傳遞
範例 #1 將 PHP Closure 指派給 C 函式指標
<?php
$zend = FFI::cdef("
typedef int (*zend_write_func_t)(const char *str, size_t str_length);
extern zend_write_func_t zend_write;
");
echo "Hello World 1!\n";
$orig_zend_write = clone $zend->zend_write;
$zend->zend_write = function($str, $len) {
global $orig_zend_write;
$orig_zend_write("{\n\t", 3);
$ret = $orig_zend_write($str, $len);
$orig_zend_write("}\n", 2);
return $ret;
};
echo "Hello World 2!\n";
$zend->zend_write = $orig_zend_write;
echo "Hello World 3!\n";
?>以上範例會輸出：
Hello World 1!
{
Hello World 2!
}
Hello World 3!
因此，建議盡量減少 PHP 回呼的使用。