如何在Perl中序列化闭包？ [英] How can I serialize a closure in Perl?

问题描述

我认为这可能是最好的例子：

  use strict; 
使用警告; 
 use 5.010; 
使用可存储qw（nstore检索）; 
 
 local $ Storable :: Deparse = 1; 
 local $ Storable :: Eval = 1; 
 
 sub sub_generator {
 my（$ x）= @_; 
 
 return sub {
 my（$ y）= @_; 
 return $ x + $ y; 
}; 
} 
 
 my $ sub = sub_generator（1000）; 
 say $ sub>（1）; ＃gives 1001 
 nstore（$ sub，/tmp/sub.store）; 
 $ sub = retrieve（/ tmp / sub.store）; 
 say $ sub>（1）; ＃gives 1 
  

当我转储 /tmp/sub.store 我看到：

  $ VAR1 = sub {
 package Storable; 
使用警告; 
 use strict'refs'; 
 my（$ y）= @_; 
 return $ x + $ y; 
} 
  

但 $ x 从来没有在这个子定义。我希望 sub_generator 生成的子代会生成 $ x ，替换为它的实际值。我应该如何解决这个问题？

请注意，此问题与此一个有关。 。

解决方案

不幸的是，我不认为 可存储 适用于闭包。但是有其他CPAN模块将序列化闭包。例如。 Data :: Dump :: Streamer

 使用5.012; 
使用警告; 
使用Data :: Dump :: Streamer; 
 
 sub sub_generator {
 my（$ x）= @_; 
 
 return sub {
 my（$ y）= @_; 
 return $ x + $ y; 
}; 
} 
 
 my $ sub = sub_generator（1000）; 
 say $ sub>（1）; ＃gives 1001 
 
 my $ serialized = Dump（$ sub） - > Out; 
 my $ copy = do {
 my $ CODE1 = undef; 
 eval $ serialized; 
 $ CODE1; 
}; 
 
 say $ copy->（2）; ＃gives 1002 
 say $ sub>（1）; ＃still gives 1001 
  

这是打印时序列化代码的样子， say Dump $ sub; ：

  my 
 $ x = 1000; 
 $ CODE1 = sub {
使用警告; 
 use strict'refs'; 
 BEGIN {
 $ ^ H {'feature_unicode'} = q（1）; 
 $ ^ H {'feature_say'} = q（1）; 
 $ ^ H {'feature_state'} = q（1）; 
 $ ^ H {'feature_switch'} = q（1）; 
} 
 my（$ y）= @_; 
 return $ x + $ y; 
}; 
  

更新
$ b

查看此主题可存储和关闭在Perl5门户邮件列表。它确认了我对 可存储 的思考和关闭。

/ I3az /

I think this might be best asked using an example:

use strict;
use warnings;
use 5.010;
use Storable qw(nstore retrieve);

local $Storable::Deparse = 1;
local $Storable::Eval    = 1;

sub sub_generator {
    my ($x) = @_;

    return sub {
        my ($y) = @_;
        return $x + $y;
    };
}

my $sub = sub_generator(1000);
say $sub->(1); # gives 1001
nstore( $sub, "/tmp/sub.store" );
$sub = retrieve("/tmp/sub.store");
say $sub->(1); # gives 1

When I dump /tmp/sub.store I see:

$VAR1 = sub {
            package Storable;
            use warnings;
            use strict 'refs';
            my($y) = @_;
            return $x + $y;
        }

But $x is never defined in this sub. I would expect that the sub generated by sub_generator will have $x replaced with its actual value upon generation. How should I solve this?

Note this question relates to this one.

解决方案

Unfortunately I don't think Storable works with closures. However there are other CPAN modules that will serialise a closure. For eg. Data::Dump::Streamer

use 5.012;
use warnings;
use Data::Dump::Streamer;

sub sub_generator {
    my ($x) = @_;

    return sub {
        my ($y) = @_;
        return $x + $y;
    };
}

my $sub = sub_generator(1000);
say $sub->(1); # gives 1001

my $serialised = Dump( $sub )->Out;
my $copy = do {
    my $CODE1 = undef;
    eval $serialised;
    $CODE1;
};

say $copy->(2); # gives 1002
say $sub->(1);  # still gives 1001

This is what the serialised code looks like when printed here, say Dump $sub;:

my ($x);
$x = 1000;
$CODE1 = sub {
           use warnings;
           use strict 'refs';
           BEGIN {
             $^H{'feature_unicode'} = q(1);
             $^H{'feature_say'} = q(1);
             $^H{'feature_state'} = q(1);
             $^H{'feature_switch'} = q(1);
           }
           my($y) = @_;
           return $x + $y;
         };

Update

See this thread Storable and Closures on the Perl5 porters mailing list. It confirms what I thought about Storable and closures.

/I3az/

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