# Shadowing outer local variable

**URL:** <https://www.ruby-forum.com/t/shadowing-outer-local-variable/129792>\
**Category:** Development\
**Created:** [February 21, 2008, 4:47pm UTC](https://www.ruby-forum.com/t/shadowing-outer-local-variable/129792 "2008-02-21T16:47:20Z")\
**Posts on this page:** 2\
**Page:** 1

<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:** [February 21, 2008, 4:47pm UTC](https://www.ruby-forum.com/t/shadowing-outer-local-variable/129792/1 "2008-02-21T16:47:20Z")

</div>

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RUBY\_VERSION # =\> “1.9.0”  
RUBY\_RELEASE\_DATE # =\> “2008-02-20”  
a = 1  
b = [1,2].map{|a| a\*2} # =\> [2, 4] # !\> shadowing outer local  
variable - a

(let ((a 1) b)  
(setq b (mapcar (lambda (a) (\* a 2)) '(1 2)))  
(list a b)) ; =\> (1 (2 4))

diff -u /home/nobackup/compile/ruby19/parse.c.orig  
/home/nobackup/compile/ruby19/parse.c  
— /home/nobackup/compile/ruby19/parse.c.orig 2008-02-22  
00:43:34.000000000 +0900  
+++ /home/nobackup/compile/ruby19/parse.c 2008-02-22 00:42:47.000000000  
+0900  
@@ -12790,7 +12790,6 @@  
yyerror(“duplicated argument name”);  
}  
else if (dvar\_defined(name) || local\_id(name)) {

- 

```
 rb_warningS("shadowing outer local variable - %s", 

```

rb\_id2name(name));  
vtable\_add(lvtbl-\>vars, name);  
}  
}

---

<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:** [February 22, 2008, 1:27am UTC](https://www.ruby-forum.com/t/shadowing-outer-local-variable/129792/2 "2008-02-22T01:27:29Z")

</div>

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In message “Re: [ruby-dev:33891] shadowing outer local variable”  
on Fri, 22 Feb 2008 00:46:10 +0900, removed\_email\_address@domain.invalid writes:

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```
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```