# Ruby-1.8.6, $SAFE=4, Proc#call

**URL:** <https://www.ruby-forum.com/t/ruby-1-8-6-safe-4-proc-call/91480>\
**Category:** Development\
**Created:** [April 9, 2007, 5:28pm UTC](https://www.ruby-forum.com/t/ruby-1-8-6-safe-4-proc-call/91480 "2007-04-09T17:28:07Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Masatoshi\_SEKI](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/5f8ce5/32.png) [@Masatoshi\_SEKI](https://www.ruby-forum.com/u/Masatoshi_SEKI)\
**Post date:** [April 9, 2007, 5:28pm UTC](https://www.ruby-forum.com/t/ruby-1-8-6-safe-4-proc-call/91480/1 "2007-04-09T17:28:07Z")

</div>

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* * *

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## safe.rb

def four\_proc(&block)  
Thread.new { $SAFE = 4; block.call }.join  
end

def four\_yield  
Thread.new { $SAFE = 4; yield }.join  
end

four\_proc { p :proc }  
four\_yield { p :yield }

## e$B\<B9T7k2Le(B

cinq:~/develop/labo/ruby/misc mas$ ruby safe.rb  
:proc  
safe.rb:10:in `write': Insecure operation`write’ at level 4  
(SecurityError)  
from safe.rb:6:in `join' from safe.rb:6:in`four\_yield’  
from safe.rb:10

---

<div class="post-metadata">

**Author:** ![Masatoshi\_SEKI](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/5f8ce5/32.png) [@Masatoshi\_SEKI](https://www.ruby-forum.com/u/Masatoshi_SEKI)\
**Post date:** [April 9, 2007, 5:40pm UTC](https://www.ruby-forum.com/t/ruby-1-8-6-safe-4-proc-call/91480/2 "2007-04-09T17:40:08Z")

</div>

e$B$^$D$b$He(B e$B$f$-$R$m$G$9e(B

In message “Re: [ruby-dev:30705] ruby-1.8.6, $SAFE=4, Proc#call”  
on Tue, 10 Apr 2007 00:27:15 +0900, Masatoshi SEKI  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

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|  
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|  
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```
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