Perl:使用 5.##.# 中包含什么？

Question

我见过好几个posts那个状态use 5.12.0;在 Perl 中默认启用某些功能/编译指示(例如， use strict; )。另一个例子是在 UTF-8 and perl据说 use 5.14.0;是

optimal for Unicode string feature UTF-8 handling.

我似乎记得一个可用的 use提供某些默认值的声明(例如， use strict; use warnings; use diagnostics; )，但不记得具体细节。如何找出给定 use 5.##.#; 中包含的内容陈述？例如，什么是use 5.22.0;默认提供？ use strict; ?

Answer 1

这记录在 perldoc feature 中:

It's possible to load multiple features together, using a feature bundle. The name of a feature bundle is prefixed with a colon, to distinguish it from an actual feature.

use feature ":5.10";

The following feature bundles are available:

bundle    features included
--------- -----------------
:default  array_base
:5.10     say state switch array_base
:5.12     say state switch unicode_strings array_base
:5.14     say state switch unicode_strings array_base
:5.16     say state switch unicode_strings
          unicode_eval evalbytes current_sub fc
:5.18     say state switch unicode_strings
          unicode_eval evalbytes current_sub fc
:5.20     say state switch unicode_strings
          unicode_eval evalbytes current_sub fc
:5.22     say state switch unicode_strings
          unicode_eval evalbytes current_sub fc

在哪里

use v5.10.0;

will do an implicit

no feature ':all';
use feature ':5.10';

and so on.

自动启用限制记录在 perldoc -f use 中:

if the specified Perl version is greater than or equal to 5.12.0, strictures are enabled lexically as with use strict.