“！”的目的是什么？和“？”在方法名称的末尾？
有时我会看到 Ruby 中的方法带有“？”和 ”！”在他们的最后，例如：
name = "sample_string"
name.reverse
name.reverse!
name.is_binary_data?
我想知道他们的目的是什么？它们只是语法糖衣吗？
Sometimes I see methods in Ruby that have "?" and "!" at the end of them, e.g:
name = "sample_string"
name.reverse
name.reverse!
name.is_binary_data?
I was wondering what their purpose is? Are they just syntax sugarcoating?
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它只是为了可读性而“糖衣”，但它们确实有共同的含义：
!结尾的方法执行一些永久性或潜在危险的更改；例如：Enumerable#sort返回对象的排序版本，而Enumerable#sort!则对其进行就地排序。ActiveRecord::Base#save返回 false，而ActiveRecord::Base#save!会引发异常。Kernel::exit导致脚本退出，而Kernel::exit!会立即执行此操作，绕过任何退出处理程序。?结尾的方法返回一个布尔值，这使得代码流程更加直观，就像一个句子 -if number.zero?读起来像“if数字为零”，但是if number.zero看起来很奇怪。在您的示例中，
name.reverse计算结果为反转字符串，但只有在name.reverse!行之后，name变量才真正包含颠倒的名称。name.is_binary_data?看起来像“name是二进制数据吗？”。It's "just sugarcoating" for readability, but they do have common meanings:
!perform some permanent or potentially dangerous change; for example:Enumerable#sortreturns a sorted version of the object whileEnumerable#sort!sorts it in place.ActiveRecord::Base#savereturns false if saving failed, whileActiveRecord::Base#save!raises an exception.Kernel::exitcauses a script to exit, whileKernel::exit!does so immediately, bypassing any exit handlers.?return a boolean, which makes the code flow even more intuitively like a sentence —if number.zero?reads like "if the number is zero", butif number.zerojust looks weird.In your example,
name.reverseevaluates to a reversed string, but only after thename.reverse!line does thenamevariable actually contain the reversed name.name.is_binary_data?looks like "isnamebinary data?".问号表示该方法返回布尔值。已经在这里回答：
问号运算符在 Ruby 中意味着什么？
感叹号表示该方法作用于物体本身。已经在这里回答：
为什么在 Ruby 方法中使用感叹号？
Question mark indicates that the method returns boolean. Already answered here:
What does the question mark operator mean in Ruby?
The bang indicates that the method acts on the object itself. Already answered here:
Why are exclamation marks used in Ruby methods?
在 Ruby 中，
?表示该方法将返回一个布尔值，而!会修改调用它的对象。它们的作用是提高查看代码时的可读性。In Ruby the
?means that the method is going to return a boolean and the!modifies the object it was called on. They are there to improve readability when looking at the code.与我认为的大多数编程语言相比......
来自： http://www.ruby-lang.org/ en/documentation/ruby-from-other-linguals/，部分有趣的方法名称
In contrast to the – I suppose – majority of programming languages ...
From: http://www.ruby-lang.org/en/documentation/ruby-from-other-languages/, Section Funny method names
请注意，情况并非总是如此。以 Ruby Array#concat http:// /docs.ruby-lang.org/en/2.0.0/Array.html#method-i-concat。
可能会严重烧毁的地方是类似
MyActiveRecordModel.column_names.concat([url])的东西。稍后与 MyActiveRecordModel 相关的调用将尝试查找 MyActiveRecordModel 的“url”列并抛出。相反，您必须在进行连接之前克隆它。幸运的是，我的测试套件发现了这个，但是..请注意！
Beware, this isn't always the case. Take for example, Ruby Array#concat http://docs.ruby-lang.org/en/2.0.0/Array.html#method-i-concat.
Where you can get burnt badly is something like
MyActiveRecordModel.column_names.concat([url]). Later calls related to MyActiveRecordModel will try to look for a column of 'url' for MyActiveRecordModel and throw.Instead you must clone it before doing the concat. Fortunately my test suite caught this one, but.. heads up!