From: Eric Hodel <drbrain@...7.net>
Date: 2005-06-03T07:58:40+09:00
Subject: Re: Interesting discovery...

On 02 Jun 2005, at 12:43, Joel VanderWerf wrote:

> Ara.T.Howard@noaa.gov wrote:
>
>>   Benchmark::bm do |b|
>>     %w(rescue_test respond_to_test).map{|m| b.report(m){c.send m,n}}
>>   end
>>   harp:~ > ruby a.rb
>>         user     system      total        real
>>   rescue_test  2.940000   0.320000   3.260000 (  3.264758)
>>   respond_to_test  0.160000   0.050000   0.210000 (  0.208268)
>> looks like respond_to? is indeed faster.
>>
>
> But if the method *is* defined, rescue is faster:
>
>   class C
>     def a; end   # <== added
>     def c; end
>
> So, if some obejcts have the methods and some dont, the best choice  
> depends on the balance between the two branches (defined vs.  
> undefined).

class C
   def a; Object.no_such_method; end
end

rescue NoMethodError is an inappropriate test for whether or not a  
method exists.  (This may or may not be important depending on what  
what else you need to rescue.)

Being faster does not make it the correct solution.

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E  7C11 332A 551C 796C 9F04