# @a?, @a! interpolation

**URL:** <https://www.ruby-forum.com/t/a-a-interpolation/136607>\
**Category:** Development\
**Created:** [May 4, 2008, 12:28pm UTC](https://www.ruby-forum.com/t/a-a-interpolation/136607 "2008-05-04T12:28:14Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [May 4, 2008, 12:28pm UTC](https://www.ruby-forum.com/t/a-a-interpolation/136607/1 "2008-05-04T12:28:14Z")

</div>

e$B0J2\<$N$h$&$K!"e(B@a?, @a! e$B$,%$%s%9%?%s%9JQ?t$H$5$l$k$N$OJQ$G$Oe(B  
e$B$J$$$G$7$g$&$+!#e(B

% ./ruby -ve ‘@a = “x”; p “[#@a?][#@a!]”’  
ruby 1.9.0 (2008-05-02 revision 16286) [i686-linux]  
-e:1: warning: instance variable @a? not initialized  
-e:1: warning: instance variable @a! not initialized  
“[][]”