Converting an empty string into nil in Ruby

问题

I have a string called word and a function called infinitive such that
word.infinitive would return another string on some occasions and an empty string otherwise
I am trying to find an elegant ruby one line expression for the code-snippet below

if word.infinitive == ""
      return word
else return word.infinitive

Had infinitive returned nil instead of "", I could have done something like

(word.infinitive or word)

But since it does not, I can't take advantage of the short-circuit OR
Ideally I would want
1) a single expression that I could easily embed in other code
2) the function infinitive being called only once
3) to not add any custom gems or plugins into my code

回答1:

If you're not ashamed of monkeypatching and abusing syntax, this would work:

class String
  def | x
    if empty? then x else self end
  end
end

Then you can say word.infinitive | word, which actually scans fairly naturally, if you ask me.

However, I think a better idea would be to modify the infinitive method, or add a version of it that returns the word unchanged.

Edit: Here's a possibly more elegant solution:

[word.infinitive, word].find {|x| not x.empty?}

回答2:

The ActiveSupport presence method converts an empty (or blank?) string to nil. It's designed for your exact use case:

word.infinitive.presence || word

Note that you can easily use ActiveSupport outside of rails:

require 'active_support/core_ext/object/blank'

回答3:

You can use a regex like this article suggests

(word.infinitive[/.+/m] or word) #Fancy way to convert "" to nil

回答4:

Do the right thing - fix infinitive so that it returns nils instead of blank strings, or wrap it with your own interface if you really can't touch it.

回答5:

You could use the ternary operator (boolean ? true-val : false-val) with String#empty?

return word.infinitive.empty? ? word : word.infinitive

if you only want to call infinitive once:

return (inf = word.infinitive).empty? ? word : inf

You may also want to consider adding some memoization to your code.

回答6:

Or you can monkeypatch a new function to String without having to abuse syntax.

class String
  def squash
    self.empty? ? nil : self
  end
end

Now you can do

puts var.squash or "default text"

I'm not a native english speaker so I don't know if squash is the best word. Is there a word that would better convey the idea of "turn into nil only if empty"?

来源：https://stackoverflow.com/questions/647370/converting-an-empty-string-into-nil-in-ruby

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ruby

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string