[ruby-core:90852] [Ruby trunk Feature#15496] Extract between string as standard String api

[shevegen@gmail.com]

Issue #15496 has been updated by shevegen (Robert A. Heiler).


Hmmm. I don't have a preference here since I can find arguments in favour or against
this. It's fairly easily possible to use a regex so .between (or any other name to 
extract the substring between two boundaries) is not that necessary; on the other hand
it may be simpler to use an "officially approved" method.

If you feel strongly about your proposal you could propose it for mention during a 
developer meeting at:

https://bugs.ruby-lang.org/issues/15462

(In ~a week or so from now on.)

Then you may get matz' opinion about the proposal, both feature-wise and API/name wise.

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Feature #15496: Extract between string as standard String api
https://bugs.ruby-lang.org/issues/15496#change-76039

* Author: macdevign (Macdevign mac)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
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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