# Object#singleton\_class

**URL:** <https://www.ruby-forum.com/t/object-singleton-class/133437>\
**Category:** Development\
**Created:** [March 31, 2008, 5:26pm UTC](https://www.ruby-forum.com/t/object-singleton-class/133437 "2008-03-31T17:26:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [March 31, 2008, 5:26pm UTC](https://www.ruby-forum.com/t/object-singleton-class/133437/1 "2008-03-31T17:26:24Z")

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class Object  
def singleton\_class  
class \<\< self; self; end  
end  
alias eigenclass singleton\_class  
alias metaclass singleton\_class  
end

x = “a”  
class \<\< x; self; end # =\> #\<Class:#String:0xb7b2c700\>  
x.singleton\_class # =\> #\<Class:#String:0xb7b2c700\>  
x.eigenclass # =\> #\<Class:#String:0xb7b2c700\>  
x.metaclass # =\> #\<Class:#String:0xb7b2c700\>

---

<div class="post-metadata">

**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [March 31, 2008, 11:12pm UTC](https://www.ruby-forum.com/t/object-singleton-class/133437/2 "2008-03-31T23:12:55Z")

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In message “Re: [ruby-dev:34191] Object#singleton\_class”  
on Tue, 1 Apr 2008 00:25:41 +0900, removed\_email\_address@domain.invalid writes:

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