blocks|key|1009884|text|我能想到的最简单的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009885|#+checking+whether+foo+is+a+boolean
!!foo+==+foo|code-block|syntax|javascript|1009886|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Simplest way I can think of:

<pre><code># checking whether foo is a boolean
!!foo == foo
</code></pre>

blocks|key|1010065|text|我发现这是简明扼要和自我记录的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010066|[true,+false].include?+foo|code-block|syntax|javascript|1010067|如果使用Rails或ActiveSupport，甚至可以使用in?进行直接查询|offset|length|style|CODE|1010068|foo.in?+[true,+false]|1010069|对于浮点数，我不建议检查所有可能的值，但当只有两个可能的值时，这是可行的！|1010070|entityMap|0|LINK|mutability|MUTABLE|url|http://guides.rubyonrails.org/active_support_core_extensions.html#in-questionmark^0|0|0|U|3|U|3|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]]|$1|G|3|H|5|6|7|10|8|@$I|11|J|12|K|L]]|9|@$I|13|J|14|1|15]]|A|$]]|$1|M|3|N|5|D|7|16|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|17|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

I find this to be concise and self-documenting:

<pre><code>[true, false].include? foo
</code></pre>

If using Rails or ActiveSupport, you can even do a direct query using <a href="http://guides.rubyonrails.org/active_support_core_extensions.html#in-questionmark"><code>in?</code></a>

<pre><code>foo.in? [true, false]
</code></pre>

Checking against all possible values isn't something I'd recommend for floats, but feasible when there are only two possible values!

blocks|key|1009847|text|如上所述，除了TrueClass和FalseClass之外，没有布尔类，但是，您可以使用任何对象作为if/除非的主语，并且除了FalseClass和nil的实例之外，所有内容都为true|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009848|布尔测试返回FalseClass或TrueClass的实例|1009849|(1+>+0).class+#TrueClass|code-block|syntax|javascript|1009850|下面的monkeypatch+to+Object将告诉你某事物是TrueClass还是FalseClass的实例|1009851|class+Object
++def+boolean?
++++self.is_a?(TrueClass)+%7C%7C+self.is_a?(FalseClass)+
++end
end|1009852|使用irb运行一些测试会得到以下结果|1009853|?>+"String".boolean?
=>+false
>>+1.boolean?
=>+false
>>+Time.now.boolean?
=>+false
>>+nil.boolean?
=>+false
>>+true.boolean?
=>+true
>>+false.boolean?
=>+true
>>+(1+==1).boolean?
=>+true
>>+(1+==2).boolean?
=>+true|1009854|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

As stated above there is no boolean class just TrueClass and FalseClass however you can use any object as the subject of if/unless and everything is true except instances of FalseClass and nil

Boolean tests return an instance of the FalseClass or TrueClass

<pre><code>(1 &gt; 0).class #TrueClass
</code></pre>

The following monkeypatch to Object will tell you whether something is an instance of TrueClass or FalseClass

<pre><code>class Object
 def boolean?
 self.is_a?(TrueClass) || self.is_a?(FalseClass) 
 end
end
</code></pre>

Running some tests with irb gives the following results

<pre><code>?&gt; "String".boolean?
=&gt; false
&gt;&gt; 1.boolean?
=&gt; false
&gt;&gt; Time.now.boolean?
=&gt; false
&gt;&gt; nil.boolean?
=&gt; false
&gt;&gt; true.boolean?
=&gt; true
&gt;&gt; false.boolean?
=&gt; true
&gt;&gt; (1 ==1).boolean?
=&gt; true
&gt;&gt; (1 ==2).boolean?
=&gt; true
</code></pre>

blocks|key|1009978|text|如果你的代码可以合理地写成case语句，这是相当不错的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009979|case+mybool
when+TrueClass,+FalseClass
++puts+"It's+a+bool!"
else
++puts+"It's+something+else!"
end|code-block|syntax|javascript|1009980|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If your code can sensibly be written as a case statement, this is pretty decent:

<pre><code>case mybool
when TrueClass, FalseClass
 puts "It's a bool!"
else
 puts "It's something else!"
end
</code></pre>

blocks|key|1224366|text|作为布尔值的对象将有一个TrueClass或FalseClass类，因此下面的一行代码应该可以解决这个问题|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1224367|mybool+=+true
mybool.class+==+TrueClass+%7C%7C+mybool.class+==+FalseClass
=>+true|code-block|syntax|javascript|1224368|下面的代码还会给出true/false布尔类型检查结果|1224369|mybool+=+true++++
[TrueClass,+FalseClass].include?(mybool.class)
=>+true|1224370|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

An object that is a boolean will either have a class of TrueClass or FalseClass so the following one-liner should do the trick

<pre><code>mybool = true
mybool.class == TrueClass || mybool.class == FalseClass
=&gt; true
</code></pre>

The following would also give you true/false boolean type check result

<pre><code>mybool = true 
[TrueClass, FalseClass].include?(mybool.class)
=&gt; true
</code></pre>

blocks|key|1010190|text|这个gem为Ruby添加了一个布尔类和一些有用的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010191|https://github.com/RISCfuture/boolean|offset|length|1010192|使用：|1010193|require+'boolean'|code-block|syntax|javascript|1010194|然后你的|1010195|true.is_a?(Boolean)
false.is_a?(Boolean)|1010196|将完全按照您的期望工作。|1010197|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|11|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@$D|11|E|12|1|13]]|A|$]]|$1|F|3|G|5|6|7|14|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|15|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|16|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|17|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|18|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|C]]]]

This gem adds a Boolean class to Ruby with useful methods.

<a href="https://github.com/RISCfuture/boolean" rel="nofollow noreferrer">https://github.com/RISCfuture/boolean</a>

Use:

<pre><code>require 'boolean'
</code></pre>

Then your

<pre><code>true.is_a?(Boolean)
false.is_a?(Boolean)
</code></pre>

will work exactly as you expect.

blocks|key|1224606|text|不是的。不像你有你的代码。没有任何名为Boolean的类。现在，有了所有的答案，您应该能够创建一个并使用它。你知道如何创建类，不是吗？我来这里只是因为我自己也想知道这个想法。很多人可能会问“为什么?你只需要知道Ruby是如何使用布尔值的”。这就是你得到答案的原因。所以谢谢你的问题。发人深省。为什么Ruby没有布尔类？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1224607|NameError:+uninitialized+constant+Boolean|code-block|syntax|javascript|1224608|请记住，对象没有类型。它们是类。对象有数据。这就是为什么当你说数据类型时，它有点用词不当。|1224609|也可以试试rand2，因为rand1似乎总是给0。随机数2会在这里给出1或0点击运行几次。https://repl.it/IOPx/7|offset|length|1224610|尽管我不知道如何自己创建一个布尔类。我用它做过实验但是..。|1224611|class+Boolean+<+TrueClass
++self
end

true.is_a?(Boolean)+#+=>+false
false.is_a?(Boolean)+#+=>+false|1224612|至少我们现在有了这个类，但是谁知道如何获得正确的值呢？|1224613|entityMap|0|LINK|mutability|MUTABLE|url|https://repl.it/IOPx/7^0|0|0|0|19|M|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|13|8|@]|9|@$K|14|L|15|1|16]]|A|$]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|18|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|19|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

No. Not like you have your code. There isn't any class named Boolean. Now with all the answers you have you should be able to create one and use it. You do know how to create classes don't you? I only came here because I was just wondering this idea myself. Many people might say "Why? You have to just know how Ruby uses Boolean". Which is why you got the answers you did. So thanks for the question. Food for thought. Why doesn't Ruby have a Boolean class?

<pre><code>NameError: uninitialized constant Boolean
</code></pre>

Keep in mind that Objects do not have types. They are classes. Objects have data. So that's why when you say data types it's a bit of a misnomer.

Also try rand 2 because rand 1 seems to always give 0. rand 2 will give 1 or 0
click run a few times here.
<a href="https://repl.it/IOPx/7" rel="nofollow noreferrer">https://repl.it/IOPx/7</a>

Although I wouldn't know how to go about making a Boolean class myself. I've experimented with it but...

<pre><code>class Boolean &lt; TrueClass
 self
end

true.is_a?(Boolean) # =&gt; false
false.is_a?(Boolean) # =&gt; false
</code></pre>

At least we have that class now but who knows how to get the right values?

I can't seem to check if an object is a boolean easily. Is there something like this in Ruby?

<pre><code>true.is_a?(Boolean)
false.is_a?(Boolean)
</code></pre>

Right now I'm doing this and would like to shorten it:

<pre><code>some_var = rand(1) == 1 ? true : false
(some_var.is_a?(TrueClass) || some_var.is_a?(FalseClass))
</code></pre>

How to check if a Ruby object is a Boolean

我似乎不能轻易地检查一个对象是否是布尔值。在Ruby中有这样的东西吗？true.is_a?(Boolean)false.is_a?(Boolean)现在我正在做这件事，我想把它缩短：some_var = rand(1) == 1 ? true : false(some_var.is_a?(TrueClass) || some_var.is_a?(FalseClass))

问如何检查Ruby对象是否为布尔值
EN

回答 7

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何检查Ruby对象是否为布尔值EN

回答 7

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何检查Ruby对象是否为布尔值
EN