PHP 5.5.0 Alpha 2 主要包含如下新特性和改进：
Support for using empty() on the result of function calls and other expressions,
Systemtap support by enabling systemtap compatible dtrace probes on linux,
Optimized access to temporary and compiled VM variables. 8% less memory reads.
请注意，该 alpha 版本同时废弃了 ext/mysql.
完整的列表可阅读 https://github.com/php/php-src/blob/php-5.5.0alpha2/NEWS
下载地址：http://downloads.php.net/dsp
来自:开源中国社区
