Issue #11929 has been updated by Yukihiro Matsumoto.

Status changed from Open to Feedback

1. ability to be duped cannot be checked by `respond_to?`. It's simply wrong.
2. the "fail silently" proposal is attractive, but it should be a separate proposal (for the sake of bookkeeping).

Matz.


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Bug #11929: No programatic way to check ability to dup/clone an object
https://bugs.ruby-lang.org/issues/11929#change-61663

* Author: xavier nayrac
* Status: Feedback
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* ruby -v: ruby 2.3.0dev (2015-12-06 trunk 52904) [i686-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
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We can't dup a Fixnum, and it's ok. But I'm wondering why is Fixnum saying it can dup?

~~~
1.respond_to?(:dup) #=> true
~~~

Don't you think that the `dup` method should be undefined in the class Fixnum?

Currently I can do `class Fixnum; undef :dup; end`, but that should be in the core Ruby, isn't it?




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