From: Ammar Ali <ammarabuali@...>
Date: 2010-10-07T13:57:31+09:00
Subject: Re: Benchmarks Project and example for `||=`

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On Thu, Oct 7, 2010 at 7:28 AM, Intransition <transfire@gmail.com> wrote:

> Has anyone ever put together a suite of benchmarks that simply measure
> interesting Ruby practices? For example, here is a comparison of using
> ||= vs not using it.
>
>  n = 1000000
>
>  puts "#{n} Times"
>
>  t = Time.now
>
>  @b = :b
>  n.times do
>    @b
>  end
>
>  puts "Simple Read : #{Time.now - t} seconds"
>
>  t = Time.now
>
>  n.times do
>    @a ||= :a
>  end
>
>  puts "  Or Equals : #{Time.now - t} seconds"
>
> On `ruby 1.8.7 (2010-01-10 patchlevel 249) [x86_64-linux]`:
>
>  1000000 Times
>  Simple Read : 0.395487 seconds
>    Or Equals : 0.508428 seconds
>
> On `ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]`:
>
>  1000000 Times
>  Simple Read : 0.121280356 seconds
>    Or Equals : 0.183629043 seconds
>
> Might be an interesting project.
>
>
It would be interesting to have performance comparisons of the various
idioms in common use.

In these examples, however, it's not surprising that the first loop (without
||=) would be faster. It's not doing anything really. The second involves
testing wether the variable is defined or not, every iteration.

Regards,
Ammar

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