Perl：解释如何使用“uni :: perl”模块 – 加载编译指示和其他

经过一番搜索CPAN后,我找到了另一个名为uni::perl的模块,这真的很复杂 – 它等同于：

use strict;
use feature qw(say state switch);
no warnings;
use warnings qw(FATAL closed threads internal debugging pack substr malloc
                unopened portable prototype inplace io pipe unpack regexp
                deprecated exiting glob digit printf utf8 layer
                reserved parenthesis taint closure semicolon);
no warnings qw(exec newline);
use utf8;
use open (:utf8 :std);
use mro 'c3';

有人可以解释/评论它是如何工作的吗？

我将整个代码粘贴到几个部分并将我的问题添加到(使用###).

我明白这个问题真的很长.但是,将它分成较小的一个将无济于事,因为整体是关于“uni :: perl”模块.

请帮助我理解有问题的部分.

package uni::perl;
use 5.010;
BEGIN {
    ### OK - these are bitmask of different warnings,they're coming from:
    # paste this into perl to find bitmask 
    # no warnings;
    # use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype
    #                 inplace io pipe unpack regexp deprecated exiting glob digit printf
    #                 utf8 layer reserved parenthesis taint closure semicolon);
    # no warnings qw(exec newline);
    # BEGIN { warn join "",map "x$_",unpack "(H2)*",${^WARNING_BITS}; exit 0 };

    ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "xfcx3fxf3x00x0fxf3xcfxc0xf3xfcx33x03";
    $^H |= 0x00000602; ### this mean "use strict;"
}

直接设置${^ WARNING_BITS}和$^ H,比常用的“use strict”等更快？

这样做m {} x.

m{
use strict;
use warnings;
}x;
use mro ();

我知道“匹配”运算符和’x’标志,但不明白在这种情况下正在做什么..使用mro是一些“黑魔法”可能是一个常见的perl用户不需要知道……;)

本地* __ ANON__线做什么？对于这个背景下的goto有什么好处？
整个下一个BEGIN块对我来说都是一个黑魔法. (

BEGIN {
    for my $sub (qw(carp croak confess)) {
        no strict 'refs';
        *$sub = sub {    ### for what need replace the global *croak (etc) with this sub?
            my $caller = caller;
            local *__ANON__ = $caller .'::'. $sub;  ### what's mean this?
            require Carp;

                    ### This set the Carp code-refs to the global namespace?
                    ### But who is the "caller" in the BEGIN block? (compile time)

            *{ $caller.'::'.$sub } = &;{ 'Carp::'.$sub };

            goto &{ 'Carp::'.$sub }; ### Why need goto here?
        };
    }
}

最后 – 一些更清晰的事情.重写导入,这将在使用uni :: perl时调用;

sub import {
    my $me = shift;
    my $caller = caller;

    ### OK - again the bitmasks
    ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "xfcx3fxf3x00x0fxf3xcfxc0xf3xfcx33x03";


    ### where are these documented?
    $^H |=
          0x00000602 # strict
        | 0x00800000 # utf8
    ;

    # use feature
    $^H{feature_switch} =
    $^H{feature_say}    =
    $^H{feature_state}  = 1;

    # use mro 'c3';
    mro::set_mro($caller,'c3');

    #use open (:utf8 :std);
    ${^OPEN} = ":utf8:utf8";
    binmode(STDIN,":utf8");
    binmode(STDOUT,":utf8");
    binmode(STDERR,":utf8");


    ### again coderef magic. As I understand it - it will replace the
    ### "carp,etc" in the callers namespace with the coderef's defined
    ### in the above BEGIN block. But why with this complicated way?

    for my $sub (qw(carp croak confess)) {
        no strict 'refs';
        *{ $caller .'::'. $sub } = &;$sub;
    }

    ### and finally - I have abosolutely no idea - what do the next code
    ### will take arguments of "use uni::perl qw(arg)"
    ### but have no idea how to use it - or what is doing ;(
    while (@_) {
        my $feature = shift;
        if ($feature =~ s/^://) {
            my $package = $me. '::'. $feature;
            eval "require $package; 1" or croak( "$@" );
            $package->load( $caller );
        }
    }
}

最后一次做什么？

加上问题：

>为什么两次做同样的事情？一旦进入BEGIN区块并进入一次？ (导入是用于“使用” – 但为什么在“BEGIN”块中也做同样的事情呢？

因为这个问题有更多部分,请在给出答案时引用相关部分.

谢谢大家.