blocks|key|1448540|text|简而言之:它将散列标记为附加到当前包名称空间(以便该包提供其类实现)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1448541|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Short version: it's marking that hash as attached to the current package namespace (so that that package provides its class implementation).

blocks|key|1448612|text|通常，bless将对象与类相关联。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1448613|package+MyClass;
my+$object+=+{+};
bless+$object,+"MyClass";|code-block|syntax|javascript|1448614|现在，当您调用$object上的方法时，Perl知道要搜索该方法的包。|1448615|如果省略了第二个参数，如您的示例所示，则使用当前包/类。|1448616|为了清楚起见，您的示例可能如下所示：|1448617|sub+new+{+
++my+$class+=+shift;+
++my+$self+=+{+};+
++bless+$self,+$class;+
}+|1448618|编辑:有关更多细节，请参阅kixx的good+answer。|1448619|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/11260/kixx|1|https://stackoverflow.com/questions/392135/what-exactly-does-perls-bless-do#392194^0|3|5|0|0|7|7|0|0|0|0|D|4|0|N|6|1|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|18|8|@$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|1B|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1C|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1E|8|@]|D|@$9|1F|A|1G|1|1H]|$9|1I|A|1J|1|1K]]|E|$]]|$1|U|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]]]

In general, <code>bless</code> associates an object with a class.

<pre><code>package MyClass;
my $object = { };
bless $object, "MyClass";
</code></pre>

Now when you invoke a method on <code>$object</code>, Perl know which package to search for the method.

If the second argument is omitted, as in your example, the current package/class is used.

For the sake of clarity, your example might be written as follows:

<pre><code>sub new { 
 my $class = shift; 
 my $self = { }; 
 bless $self, $class; 
} 
</code></pre>

EDIT: See <a href="https://stackoverflow.com/users/11260/kixx">kixx</a>'s good <a href="https://stackoverflow.com/questions/392135/what-exactly-does-perls-bless-do#392194">answer</a> for a little more detail.

blocks|key|1448713|text|bless将引用与包关联。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1448714|引用是什么并不重要，它可以是散列(最常见的情况)、数组(不常见的情况)、标量(通常表示inside-out+object)、正则表达式、子例程或TYPEGLOB+(有关有用的示例，请参阅Object+Oriented+Perl:+A+Comprehensive+Guide+to+Concepts+and+Programming+Techniques+by+Damian+Conway一书)，甚至可以是对文件或目录句柄的引用(最不常见的情况)。|1448715|bless-ing的作用在于，它允许您将特殊语法应用于受祝福的引用。|1448716|例如，如果一个有福的引用存储在$obj中(通过bless与包“Class”相关联)，那么$obj->foo(@args)将调用子例程foo，并将引用$obj作为第一个参数传递，随后是其余参数(@args)。子例程应该在"Class“包中定义。如果“类”包中没有子例程foo，将搜索其他包的列表(取自包“类”中的数组@ISA+)，并调用找到的第一个子例程foo。|1448717|entityMap|0|LINK|mutability|MUTABLE|url|https://perldoc.perl.org/perlobj.html#Inside-Out-objects|1|https://www.goodreads.com/book/show/86378.Object_Oriented_Perl^0|0|5|0|17|H|0|2L|2R|1|0|0|5|0|F|4|N|5|18|G|1U|3|22|4|2O|5|3P|3|4D|4|4W|3|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@]|D|@$9|Z|A|10|1|11]|$9|12|A|13|1|14]]|E|$]]|$1|H|3|I|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]|$9|1J|A|1K|B|C]|$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]]|D|@]|E|$]]|$1|L|3|-4|5|6|7|1R|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S]]|T|$5|O|P|Q|E|$R|U]]]]

<code>bless</code> associates a reference with a package. 

It doesn't matter what the reference is to, it can be to a hash (most common case), to an array (not so common), to a scalar (usually this indicates an <a href="https://perldoc.perl.org/perlobj.html#Inside-Out-objects" rel="noreferrer">inside-out object</a>), to a regular expression, subroutine or TYPEGLOB (see the book <a href="https://www.goodreads.com/book/show/86378.Object_Oriented_Perl" rel="noreferrer">Object Oriented Perl: A Comprehensive Guide to Concepts and Programming Techniques by Damian Conway</a> for useful examples) or even a reference to a file or directory handle (least common case).

The effect <code>bless</code>-ing has is that it allows you to apply special syntax to the blessed reference. 

For example, if a blessed reference is stored in <code>$obj</code> (associated by <code>bless</code> with package "Class"), then <code>$obj-&gt;foo(@args)</code> will call a subroutine <code>foo</code> and pass as first argument the reference <code>$obj</code> followed by the rest of the arguments (<code>@args</code>). The subroutine should be defined in package "Class". If there is no subroutine <code>foo</code> in package "Class", a list of other packages (taken form the array <code>@ISA</code> in the package "Class") will be searched and the first subroutine <code>foo</code> found will be called.

blocks|key|1663656|text|例如，如果您可以确信任何Bug对象都将是一个受祝福的散列，那么您就可以(终于！)填充Bug::print_me方法中缺少的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1663657|+package+Bug;
+sub+print_me
+{
+++++my+($self)+=+@_;
+++++print+"ID:+$self->{id}\n";
+++++print+"$self->{descr}\n";
+++++print+"(Note:+problem+is+fatal)\n"+if+$self->{type}+eq+"fatal";
+}|code-block|syntax|javascript|1663658|现在，每当通过引用已被赋予Bug类的任何散列来调用print_me方法时，$self变量提取作为第一个参数传递的引用，然后print语句访问被赋予的散列的各个条目。|1663659|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

For example, if you can be confident that any Bug object is going to be a blessed hash, you can (finally!) fill in the missing code in the Bug::print_me method:

<pre><code> package Bug;
 sub print_me
 {
 my ($self) = @_;
 print "ID: $self-&gt;{id}\n";
 print "$self-&gt;{descr}\n";
 print "(Note: problem is fatal)\n" if $self-&gt;{type} eq "fatal";
 }
</code></pre>

Now, whenever the print_me method is called via a reference to any hash that's been blessed into the Bug class, the $self variable extracts the reference that was passed as the first argument and then the print statements access the various entries of the blessed hash.

blocks|key|1448836|text|我遵循这一思想来指导面向对象Perl的开发。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1448837|请将任何数据结构引用与类相关联。给定Perl如何创建继承结构(在一种树中)，可以很容易地利用对象模型来创建用于组合的对象。|1448838|对于这种关联，我们称为对象，以开发始终牢记，对象的内部状态和类行为是分开的。您可以允许/允许任何数据引用使用任何包/类行为。因为包可以理解对象的“情绪”状态。|1448839|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

I Following this thought to guide the development object-oriented Perl.

Bless associate any data structure reference with a class. Given how Perl creates the inheritance structure (in a kind of tree) it is easy to take advantage of the object model to create Objects for composition.

For this association we called object, to develop always have in mind that the internal state of the object and class behaviours are separated. And you can bless/allow any data reference to use any package/class behaviours.
Since the package can understand "the emotional" state of the object.

I understand one uses the "bless" keyword in Perl inside a class's "new" method:

<pre><code>sub new {
 my $self = bless { };
 return $self;
} 
</code></pre>

But what exactly is "bless" doing to that hash reference ?

What exactly does Perl's "bless" do?

数据结构

Perl

据我所知，在类的"new“方法中使用Perl中的"bless”关键字：sub new {    my $self = bless { };    return $self;}    但是“上帝保佑”到底对那个散列引用做了什么呢？

问Perl的“上帝保佑”到底做了什么？
EN

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