[ruby-core:90884] [Ruby trunk Feature#15496] Extract between string as standard String api

[duerst@it.aoyama.ac.jp]

Issue #15496 has been updated by duerst (Martin Dürst).


macdevign (Macdevign mac) wrote:

> Given that string "between" extraction is such a common operation,

Can you back that up with some additional information/data? For example, do you know other programming languages that have such a function/method?

I haven't had the need for such a method, and use cases I can think of very quickly need additional or different parameters (such as xth occurrence, between (Regexp) patterns rather than simple strings, before or after a string,...), which suggests to me that solving this specific problem with the general regular expression functionality already in Ruby.


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Feature #15496: Extract between string as standard String api
https://bugs.ruby-lang.org/issues/15496#change-76071

* Author: macdevign (Macdevign mac)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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I could not find the a simple String api to extract the string between two string, and I notice that many face the same issue and endup rolling their own solutions (eg https://stackoverflow.com/questions/9661478/how-to-return-the-substring-of-a-string-between-two-strings-in-ruby). 

Given that string "between" extraction is such a common operation, will adding a focused and simplified String method  make coding pleasant ?

This is my solution but probably someone can provide better and efficient implementation.

~~~
  # self: String instance, 
  # from: first 'from' String  
  # to:  first 'to' String found after 'from'
  # return string between from and to, which exclude the argument, nil otherwise.

  def between(from, to)
      from_idx = self.index(from)&.+(from.length)
      if from_idx
        to_idx = self.index(to, from_idx)
        return self[from_idx...to_idx] if to_idx
      end
      nil
    end
~~~

Test case

"Hello world".between("ell", "ld") => "o wor"
"Testing 123".between("Te", "123") => "sting "





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