From: Stefan Kaes <skaes@...>
Date: 2006-01-12T20:47:07+09:00
Subject: Re: Looking up properties and speed

Jonathan Leighton wrote:
> Hi,
>
> In Javascript, if one were to use the same property value twice or more,
> one would store it in a local variable because looking up the property
> slows things down.
>
> Is the situation the same in Ruby? Is there any speed difference between
> these:
>
> def foo
>   val = obj.prop
>   puts val
>   puts val
> end
>
> def boo
>   puts obj.prop
>   puts obj.prop
> end
>
> I assume not because I think the reason it's like that with Javascript
> is because of the DOM (yeah, that's not strictly Javascript).
>
> Cheers
>
>   

Accessing a property involves a function call, which is probably slower 
than caching the value in a local variable. Even more so if the 
computation of the property value is expensive. However, I would worry 
about the speed difference only when the coding path is an application 
hot spot.

-- stefan

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