Issue #9865 has been reported by Akira Tanaka.

----------------------------------------
Bug #9865: frozen IO object causes RuntimeError with inspect and fileno
https://bugs.ruby-lang.org/issues/9865

* Author: Akira Tanaka
* Status: Open
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.2.0dev (2014-05-27 trunk 46150) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
IO object を freeze すると、inspect や fileno が RuntimeError になるんですが、
これはよろしくないんじゃないかと思います。

```
% ./ruby -e 'f = open("."); f.freeze; p f'       
-e:1:in `inspect': can't modify frozen File (RuntimeError)
	from -e:1:in `p'
	from -e:1:in `<main>'
% ./ruby -e 'f = open("."); f.freeze; p f.fileno'
-e:1:in `fileno': can't modify frozen File (RuntimeError)
	from -e:1:in `<main>'
% ./ruby -v
ruby 2.2.0dev (2014-05-27 trunk 46150) [x86_64-linux]
```

あるいは、なにか理由がありましたっけ?




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