Issue #14360 has been updated by shevegen (Robert A. Heiler).


> This issue is also open in its repository because it's not clear to me
> where is the appropriate place to open the issue

Don't worry - the tracker here is still the official bug/feature/misc
tracker for the ruby language. Github issues are secondary and often
primarily useful for patchsets/pull requests. The ruby core team often
encourages people to write an issue tracker here at bugs.ruby-lang.org
rather than just on github alone.

To the issue at hand, I know way too little to really meaningfully comment
on it but I think that this may indeed be a regression. At the least I
can not think of a deliberate change to have different behaviour there.

https://www.ruby-lang.org/en/news/2017/12/25/ruby-2-5-0-released/ does
not list any notable change in the CSV module. Possibly a test can
ensure the functionality to remain the same (if it is a regression)
in this context.

----------------------------------------
Bug #14360: Regression CSV#open method for writing from Ruby 2.4.3 to 2.5.0
https://bugs.ruby-lang.org/issues/14360#change-69583

* Author: arturoherrero (Arturo Herrero)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17]
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN
----------------------------------------
I have noticed a different behaviour between Ruby <= 2.4.3 and Ruby 2.5.0 for the `#open` method.

This issue is also open in its repository because it's not clear to me where is the appropriate place to open the issue, https://github.com/ruby/csv/issues/17

If you create an empty file for writing and you are not writing any line in that CSV file, Ruby <= 2.4.3 doesn't write anything (an empty file) but Ruby 2.5.0 writes the headers.

### Ruby <= 2.4.3
```shell
$ ruby -v
ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17]
```

```ruby
$ irb
irb(main):001:0> require "csv"
=> true
irb(main):002:0> CSV.open("ruby-2.4.3.csv", "wb", headers: ["name", "surname"], write_headers: true) { }
=> nil
irb(main):003:0> `cat ruby-2.4.3.csv`
=> ""
```


### Ruby 2.5.0
```shell
$ ruby -v
ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17]
```

```ruby
$ irb
irb(main):001:0> require "csv"
=> true
irb(main):002:0> CSV.open("ruby-2.5.0.csv", "wb", headers: ["name", "surname"], write_headers: true) { }
=> nil
irb(main):003:0> `cat ruby-2.5.0.csv`
=> "name,surname\n"
```

---

In the examples, I'm using an empty block but in a real application probably you will have an `if` statement, something like this:

```ruby
CSV.open(...) do |csv|
  csv << "hello" if condition
end
```



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

Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>