Issue #14240 has been updated by Eregon (Benoit Daloze).


I agree.
These global variables can only be useful in tiny scripts,
and even then I believe none of them are idiomatic Ruby code.

All of these are shortcuts saving at best a couple characters,
but also threaten any usage of gets/print/split/join methods in larger programs.
Giving an argument gets/print/split/join is much clearer and safer.

I was already thinking along the same lines 6 years ago about $, in https://bugs.ruby-lang.org/issues/5977,
after being caught by a bug of some library setting $, and breaking the rest in very surprising ways iirc.

----------------------------------------
Bug #14240: warn four special variables: $; $, $/ $\
https://bugs.ruby-lang.org/issues/14240#change-69003

* Author: akr (Akira Tanaka)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN
----------------------------------------
I think the four special variables for separators should be deprecated.

```
$/    input record separator (default argument for "gets")
$\    output record separator ("print" prints it at last)
$,    default separator for Array#join and print
$;    default separator for String#split
```

I feel many program doesn't work if they are set to non-default value.

Since they are global, not thread local,
we can not change these variables safely in a multi threaded program.

So, I think we should warn them (and delete them in future).







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