From: Logan Capaldo <logancapaldo@...>
Date: 2006-07-15T02:45:22+09:00
Subject: Re: Preferred monkeypatching technique


On Jul 14, 2006, at 1:26 PM, Eric Hodel wrote:

> On Jul 14, 2006, at 10:02 AM, Logan Capaldo wrote:
>> Neat idea, gensym in Ruby. I would suggest making it thread-safe  
>> though:
>>
>> % cat gensym.rb
>> require 'mutex'
>> class Symbol
>>   GensymLock = Mutex.new
>>   def self.gensym
>>     GensymLock.synchronize {
>>       @@gensym_count ||= 0
>>       @@gensym_count += 1
>>       ("__gensym__%X" % @@gensym_count).intern
>>     }
>>   end
>> end
>
> You don't need a mutex.
>
> class Symbol
>   @gensym_count = 0
>   def self.gensym
>     ("__gensym__%X" % @gensym_count += 1).intern
>   end
> end
>

Do you not need a Mutex _now_, since @gensym_count += 1 is  
effectively atomic in current ruby, or will you _never_ need a mutex?

What if?

thread 1:
   @gensym_count += 1
thread 2:
   @gensym_count += 1

thread 1:
   interpolate and intern
thread 2
   interpolate and intern

I guess it's ok since a = expr is always supposed to return expr not  
a, but it leaves a bad taste in my mouth.

> -- 
> Eric Hodel - drbrain@segment7.net - http://blog.segment7.net
> This implementation is HODEL-HASH-9600 compliant
>
> http://trackmap.robotcoop.com
>
>
>