Perl 5.004 was released on May 15, 1997, and included among other things the UNIVERSAL package, giving Perl a base object to which all classes were automatically derived and the ability to require versions of modules.
Perl 5.004于1997年5月15日发布，添加了UNIVERSAL包，这给了Perl一个所有的类的基础和要求使用模块的特定版本的能力。