From: Charlie Somerville <charlie@...>
Date: 2013-02-14T09:38:32+09:00
Subject: [ruby-core:52236] Re: [ruby-trunk - Feature #7839] Symbol.freeze_symbols

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On Thursday, 14 February 2013 at 11:30 AM, Aaron Patterson wrote:
> Yes, this is probably not thread safe, but if people *know* it's not
> thread safe, then they can lock:
> 
> begin
> Symbol.lock
> Symbol.freeze_symbols
> YAML.load(...)
> ensure
> Symbol.thaw_symbols
> Symbol.unlock
> end

I think this is a perfect contender for a block. There can be a global 'symbol_freeze_count' that is incremented when the block enters, and decremented on the way out. 

For example:

  Symbol.frozen do
    :foo # ok because this is symbol-ified by the parser beforehand
    eval ":foo" # exception
    "foo".to_sym # exception
  end

This is better because it is re-entrant, unlike a pair of 'freeze' and 'thaw' methods.
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                <div><span style=3D=22color: rgb(160, 160, 168); =22>On T=
hursday, 14 =46ebruary 2013 at 11:30 AM, Aaron Patterson wrote:</span></d=
iv>
                <blockquote type=3D=22cite=22 style=3D=22border-left-styl=
e:solid;border-width:1px;margin-left:0px;padding-left:10px;=22>
                    <span><div>Yes, this is probably not thread safe, but=
 if people *know* it's not</div><div>thread safe, then they can lock:</di=
v><div><br></div><div>    begin</div><div>      Symbol.lock</div><div>   =
   Symbol.freeze=5Fsymbols</div><div>      YAML.load(...)</div><div>    e=
nsure</div><div>      Symbol.thaw=5Fsymbols</div><div>      Symbol.unlock=
</div><div>    end</div></span></blockquote><div>I think this is a perfec=
t contender for a block. There can be a global 'symbol=5Ffreeze=5Fcount' =
that is incremented when the block enters, and decremented on the way out=
.
                </div><div><br></div><div>=46or example:</div><div><br></=
div><div>&nbsp; Symbol.frozen do</div><div>&nbsp; &nbsp; :foo =23 ok beca=
use this is symbol-ified by the parser beforehand</div><div>&nbsp; &nbsp;=
 eval =22:foo=22 =23 exception</div><div>&nbsp; &nbsp; =22foo=22.to=5Fsym=
 =23 exception</div><div>&nbsp; end</div><div><br></div><div>This is bett=
er because it is re-entrant, unlike a pair of 'freeze' and 'thaw' methods=
.</div>
            
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