From: "jeremyevans0 (Jeremy Evans)" <noreply@...>
Date: 2022-06-10T15:46:51+00:00
Subject: [ruby-core:108853] [Ruby master Bug#18768] Inconsistent behavior of IO, StringIO and String each_line methods when return paragraph and chomp: true passed

Issue #18768 has been updated by jeremyevans0 (Jeremy Evans).


mame (Yusuke Endoh) wrote in #note-8:
> @jeremyevans0 Thank you for your explanation, I understand. The keyword name "chomp" might be a bit confusing.

I agree, the behavior is not obvious from the name `chomp`.  However, it is obvious that `chomp` is supposed to remove the separator and not the generic newline.  You can see this when providing an explicit line ending character:

```ruby
'abc'.each_line('b', chomp: true).to_a
# => ["a", "c"]

require 'stringio'
StringIO.new('abc').each_line('b', chomp: true).to_a
# => ["a", "c"]

r, w = IO.pipe
w.write('abc')
w.close
r.each_line('b', chomp: true).to_a
# => ["a", "c"]
```

----------------------------------------
Bug #18768: Inconsistent behavior of IO, StringIO and String each_line methods when return paragraph and chomp: true passed
https://bugs.ruby-lang.org/issues/18768#change-97932

* Author: andrykonchin (Andrew Konchin)
* Status: Open
* Priority: Normal
* ruby -v: 3.0.3
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
In IO, StringIO and String methods that return lines (e.g. `each`, `each_line`, `gets`, `readline`, `readlines`) behave in a different way when the following parameters are passed
- separator is `""` and
- `chomp` is `true`.

They truncate the new line characters between paragraphs and the trailing one differently:

```ruby
"a\n\nb\n\nc\n".each_line("", chomp: true).to_a
#=> ["a\n", "b\n", "c\n"]

StringIO.new("a\n\nb\n\nc\n").each_line("", chomp: true).to_a
#=> ["a\n", "b\n", "c"]

File.open('chomp.txt').each_line("", chomp: true).to_a
#=> ["a", "b", "c\n"]
```

The text file content is the same:

```ruby
File.read('chomp.txt')
#=> "a\n\nb\n\nc\n"
```

Expected behavior - they return the same result.



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