blocks|key|301909|text|在更多的搜索中，我找到了至少部分问题的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|301910|基于：http://wikis.onestepback.org/index.cgi/Tech/Ruby/RubyBindings.rdoc/style/print|offset|length|301911|剩下的是在Jim+Shubert的有用的指针之后的实验。|301912|301913|这可以通过绑定中的eval-ing+local_variables，instance_variables和global_variables来完成。|ordered-list-item|style|CODE|301914|您可以按照下面的描述做一些事情，给定var_name，<代码>D10，<代码>D11(语法可能不完善或不完善，请在评论中提出建议。而且，我不能让代码格式化在列表中工作，关于如何做的建议也可以直接使用implemented.)|301915|You+(2)并循环哈希来完成。|301916|参见下面的第二个代码块。我们的想法是从TOPLEVEL_BINDING开始，我认为它通常只包括全局变量。|301917|301918|这确实涉及到使用字符串eval。然而，任何变量值都不会扩展到所涉及的字符串中，所以如果按照描述的方式使用它应该是相当安全的，并且应该可以“传入”复杂的变量值。|301919|还要注意，总是可以执行eval+var_name,+my_binding来获取变量的值。请注意，在所有这些用法中，至关重要的是变量的名称对于计算是安全的，因此理想情况下，变量的名称不应该来自任何类型的用户输入。|301920|在给定var_name、new_val、my_binding的绑定内设置变量|301921|#+the+assignment+to+nil+in+the+eval+coerces+the+variable+into+existence+at+the+outer+scope
setter+=+eval+"#{var_name}+=+nil;+lambda+{+%7Cv%7C+#{var_name}+=+v+}",+my_binding
setter.call(new_val)|code-block|syntax|javascript|301922|构建“定制”绑定：|301923|my_binding+=+eval+"lambda+{+binding+}",+TOPLEVEL_BINDING+#+build+a+nearly-empty+binding
#+set_in_binding+is+based+on+the+above+snippet
vars_to_include.each+{+%7Cvar_name,+new_val%7C+set_in_binding(var_name,+new_val,+my_binding)+}|301924|entityMap|0|LINK|mutability|MUTABLE|url|http://wikis.onestepback.org/index.cgi/Tech/Ruby/RubyBindings.rdoc/style/print^0|0|3|26|0|0|0|0|9|4|I|F|Y|I|1H|G|0|I|8|0|0|0|0|B|4|0|B|P|0|3|8|C|7|K|A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1I|8|@]|9|@$D|1J|E|1K|1|1L]]|A|$]]|$1|F|3|G|5|6|7|1M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|1O|8|@$D|1P|E|1Q|L|M]|$D|1R|E|1S|L|M]|$D|1T|E|1U|L|M]|$D|1V|E|1W|L|M]]|9|@]|A|$]]|$1|N|3|O|5|K|7|1X|8|@$D|1Y|E|1Z|L|M]]|9|@]|A|$]]|$1|P|3|Q|5|K|7|20|8|@]|9|@]|A|$]]|$1|R|3|S|5|K|7|21|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|22|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|23|8|@$D|24|E|25|L|M]]|9|@]|A|$]]|$1|W|3|X|5|6|7|26|8|@$D|27|E|28|L|M]]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|29|8|@$D|2A|E|2B|L|M]|$D|2C|E|2D|L|M]|$D|2E|E|2F|L|M]]|9|@]|A|$]]|$1|10|3|11|5|12|7|2G|8|@]|9|@]|A|$13|14]]|$1|15|3|16|5|6|7|2H|8|@]|9|@]|A|$]]|$1|17|3|18|5|12|7|2I|8|@]|9|@]|A|$13|14]]|$1|19|3|-4|5|6|7|2J|8|@]|9|@]|A|$]]]|1A|$1B|$5|1C|1D|1E|A|$1F|1G]]]]

On searching more, I found an answer to at least part of my question:

Based on: <a href="http://wikis.onestepback.org/index.cgi/Tech/Ruby/RubyBindings.rdoc/style/print" rel="noreferrer">http://wikis.onestepback.org/index.cgi/Tech/Ruby/RubyBindings.rdoc/style/print</a>

The rest is from experimentation after Jim Shubert's helpful pointers.

<ol>
<li>This can be accomplished by <code>eval</code>-ing <code>local_variables</code>, <code>instance_variables</code> and <code>global_variables</code> inside the binding.</li>
<li>You can do something as described below, given <code>var_name</code>, <code>new_val</code>, <code>my_binding</code> (syntax may be imperfect or improvable, feel free to suggest in comments. Also, I couldn't get the code formatting to work inside the list, suggestions for how to do that will also be implemented.)</li>
<li>You can straightforwardly take (2) and loop the hash to do this.</li>
<li>See the second code block below. The idea is to start with TOPLEVEL_BINDING, which I believe normally just includes the global variables.</li>
</ol>

This does involve using string <code>eval</code>. However, no variable values are ever expanded into the strings involved, so it should be fairly safe if used as described, and should work to 'pass in' complex variable values.

Also note that it's always possible to do <code>eval var_name, my_binding</code> to get a variable's value. Note that in all of these uses it's vital that the variable's name be safe to eval, so it should ideally not come from any kind of user input at all.

Setting a variable inside a binding given <code>var_name</code>, <code>new_val</code>, <code>my_binding</code>:

<pre><code># the assignment to nil in the eval coerces the variable into existence at the outer scope
setter = eval "#{var_name} = nil; lambda { |v| #{var_name} = v }", my_binding
setter.call(new_val)
</code></pre>

Building a "bespoke" binding:

<pre><code>my_binding = eval "lambda { binding }", TOPLEVEL_BINDING # build a nearly-empty binding
# set_in_binding is based on the above snippet
vars_to_include.each { |var_name, new_val| set_in_binding(var_name, new_val, my_binding) }
</code></pre>

blocks|key|3036937|text|沃尔特，你应该能够直接与绑定交互。我以前没有太多的绑定工作，但我在irb中运行了一些东西：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3036938|jim@linux-g64g:~>+irb
irb(main):001:0>+eval+"self",+TOPLEVEL_BINDING
=>+main
irb(main):002:0>+eval+"instance_variables",+TOPLEVEL_BINDING
=>+[]
irb(main):003:0>+eval+"methods",+TOPLEVEL_BINDING
=>+["irb_kill",+"inspect",+"chws",+"install_alias_method",+....|code-block|syntax|javascript|3036939|我还有一个元编程Ruby，它并没有太多关于绑定的内容。但是，如果你拿起这个，在144页的末尾写着|3036940|3036941|在某种意义上，您可以将绑定对象看作是比块更“纯粹”的闭包形式，因为这些对象包含作用域，但不包含代码。|blockquote|3036942|3036943|3036944|而且，在相反的页面上，它建议修改irb的代码(删除eval调用的最后两个参数)，以了解它是如何使用绑定的：|3036945|//+ctwc/irb/workspace.rb|3036946|eval(statements，@binding)+#，file，line)|3036947|还有..。我本打算建议传递lambda，但我看到您刚刚回答了这个问题，所以我将把irb修修补补作为进一步研究的建议。|3036948|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|11|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|12|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|13|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|14|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|15|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|16|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|17|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|18|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|X|$]]

Walter, you should be able to interact directly with the binding. I haven't worked much with bindings before, but I ran a couple of things in irb:

<pre><code>jim@linux-g64g:~&gt; irb
irb(main):001:0&gt; eval "self", TOPLEVEL_BINDING
=&gt; main
irb(main):002:0&gt; eval "instance_variables", TOPLEVEL_BINDING
=&gt; []
irb(main):003:0&gt; eval "methods", TOPLEVEL_BINDING
=&gt; ["irb_kill", "inspect", "chws", "install_alias_method", ....
</code></pre>

I also have Metaprogramming Ruby which doesn't talk a whole lot about binding. However, if you pick this up, at the end of page 144 it says 

<blockquote>
 In a sense, you can see Binding
 objects as a "purer" form of closures
 than blocks, because these objects
 contain a scope but don't contain
 code.
</blockquote>

And, on the opposite page, it suggests tinkering with irb's code (removing the last two args to the eval call) to see how it uses bindings:

// ctwc/irb/workspace.rb 
eval(statements, @binding) #, file, line)

And... I was going to suggest passing the lambda, but I see you just answered that, so I'll leave the irb tinkering as a suggestion for further research.

I'm rather new to Ruby, and so far, figuring out how to use <a href="http://ruby-doc.org/core/classes/Binding.html" rel="noreferrer">"binding" objects</a> is one of the biggest pain points for me. If I'm reading the documentation correctly, they're almost entirely opaque. To access the scope inside the binding object, you have to have a string of Ruby code and <a href="http://ruby-doc.org/core/classes/Kernel.html#M005922" rel="noreferrer">eval</a> it using the binding.

Maybe I'm just a purist from a different school, but I'm allergic to string-based 'eval' constructs, generally speaking. Is there any way to do any of the following, securely and in the general case, given a binding object:

<ol>
<li>List the identifiers in scope in the context the binding represents, or retrieve a hash of the contents.</li>
<li>Set the value of a local variable in the binding equal to that of some local variable in an external context. Ideally, this should work generally, even if the value is an object reference, file handle, or some other complex entity.</li>
<li>(extension 2:) Given a hash, set locals in the binding for each entry.</li>
<li>Better yet, given a hash build a binding with only the basic language constructs and the names in the hash in scope.</li>
</ol>

Basically, I want to know which of those is possible and how to accomplish the ones that are. I imagine that the solutions for each will be fairly closely related, which is why I'm putting all of this in a single question.

Alternatively, is there any way to eval code that's already been parsed in the context of a binding, similar to Perl's eval BLOCK syntax?

Is 'eval' the only way to interact with binding objects in Ruby?

我是Ruby的新手，到目前为止，弄清楚如何使用是我最大的痛点之一。如果我没看错文档，它们几乎是完全不透明的。要访问binding对象中的作用域，您必须拥有一个Ruby代码字符串，并使用绑定对其进行。也许我只是一个来自不同学校的纯粹主义者，但一般来说，我对基于字符串的'eval‘构造过敏。在给定绑定对象的情况下，是否有任...

问'eval‘是在Ruby中与绑定对象交互的唯一方式吗？
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