[ruby-core:43034] [ruby-trunk - Feature #5120] String#split needs to be logical

Issue #5120 has been updated by Alexey Muranov.


I would like add a use case which may be not very useful, but in my opinion illustrates the issue well.

I wanted to normalize some mistyped email addresses in a database and i did like this (because i forgot about this issue):

email.split('@').map(&:strip).join('@')

This works for complete email address, but when i ran into

' sam @ '.split('@').map(&:strip).join('@') # => 'sam@'

but

'jim@'.split('@').map(&:strip).join('@') # => 'jim'

i decided to change to

email.split('@', -1).map(&:strip).join('@')

which does not make it more readable (sarcasm :-)).
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Feature #5120: String#split needs to be logical
https://bugs.ruby-lang.org/issues/5120

Author: Alexey Muranov
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


I would call this a bug, but i am new to Ruby, so i report this as a feature request.

Here are examples showing a surprising and inconsistent behavior of String#split method:

"aa".split('a')  # => []
"aab".split('a')  # => ["", "", "b"]

"aaa".split('aa')  # => ["", "a"] 
"aaaa".split('aa')  # => []
"aaaaa".split('aa')  # => ["", "", "a"] 

"".split('')  # => []
"a".split('')  # => ["a"]

What is the definition of *split*?
In my opinion, there should be given a simple one that would make it clear what to expect.
For example:

  str1.split(str2) returns a maximal array of non-empty substrings of str1 which can be concatenated with copies of str2 to form str1.

Additional precisions can be made to this definition to make clear what to expect as the result of "baaab".split("aa").

Thanks for attention.


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