# Class#dup

**URL:** <https://www.ruby-forum.com/t/class-dup/140547>\
**Category:** Development\
**Created:** [June 16, 2008, 4:11am UTC](https://www.ruby-forum.com/t/class-dup/140547 "2008-06-16T04:11:07Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![SASADA\_Koichi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f1d935/32.png) [@SASADA\_Koichi](https://www.ruby-forum.com/u/SASADA_Koichi)\
**Post date:** [June 16, 2008, 4:11am UTC](https://www.ruby-forum.com/t/class-dup/140547/1 "2008-06-16T04:11:07Z")

</div>

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e$B$$$&%l%]!\<%H$r$b$i$$$^$7$?!%e(B

class A  
@@a = ‘A’  
def a=(x)  
@@a = x  
end  
def a  
@@a  
end  
end

B = A.dup  
B.new.a = ‘B’  
p A.new.a #=\> ‘B’  
#=\> 1.8.7 e$B$@$He(B ‘A’

e$B!!$[$H$s$I!$e(BClass#dup  
e$B$N$3$H$r9M$($F$$$J$+$C$?$N$G$9$,!$$3$NLdBj$O??e(B  
e$BLLL$K\<h$j07$&I,MW$,$"$k$G$7$g$&$+!%Nc$($P!$e(BClass#dup  
e$B$O%5%]!\<%H$7$Je(B  
e$B$$!$$H$$$&$N$b\<j$+$H;W$$$^$9!%$d$O$j$3$l$OI,MW$J5!G=$@!$$H??LLL$K9Me(B  
e$B$($k$J$i!$$,$i$j$HFbIt9=B$$rJQ99$9$kI,MW$,$"$j$^$9!%$b$7I,MW$J$i!$e(B  
1.9.0-3 e$B$^$G$K4V$K9g$&$h$&$KJQ99$7$?$$$H;W$$$^$9!%e(B

e$B!!$A$J$_$K!$\<!$N$h$&$JNc$r;n$7$F$_$?$H$3$m!$e(B1.8.7  
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e$B$j$^$7$?!%e(B

class A  
Const = ‘A’  
def foo  
p Const  
end  
end

B = A.dup

class B  
Const = ‘B’  
end

p A::Const  
A.new.foo  
p B::Const  
B.new.foo # 1.8.6 e$B0JA0!$e(B1.9.0 ‘A’  
# 1.8.7 e$B$@$H%(%i!\<!%$3$l$O%P%0$C$]$$!%e(B

---

<div class="post-metadata">

**Author:** ![SASADA\_Koichi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f1d935/32.png) [@SASADA\_Koichi](https://www.ruby-forum.com/u/SASADA_Koichi)\
**Post date:** [July 8, 2008, 12:24pm UTC](https://www.ruby-forum.com/t/class-dup/140547/2 "2008-07-08T12:24:10Z")

</div>

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