From: Dave Howell <groups@...>
Date: 2006-06-02T05:55:02+09:00
Subject: Re: How use Profiling, a Quick Guide.


On Jun 1, 2006, at 13:47, Victor Shepelev wrote:

> From: Dave Howell [mailto:groups@grandfenwick.net]
> Sent: Thursday, June 01, 2006 11:36 PM
>>>>> * Large number of calls to .size and .length and .count_objects
>>>>> methods are a
>>>>>   clue some nidjit somewhere is doing something really N^2 stupid
>>>>> like...
>>>>>    for( i=0; i < container.count_objects(); i++) {
>>>>>    }
>>>>
>>>> question_stack << "What exactly is stupid about that? And what's the
>>>> smart alternative?
>>> max=container.count_objects()
>>> for( i=0; i < max; i++) {
>>> }
>>>
>>> container.each....
>>
>> OK, so "container.each" is presumably the smart alternative, and what
>> I'd instinctively use anyway, but I don't understand what it is about
>> "for( i=0; i < max; i++)" that makes it "really n^2 stupid."
>
> The point was: if you use some value repeatedly, it is generally 
> smarter to
> pre-calculate it.

{brief scratching of head}

Oh! So BOTH of Sam's examples were 'non-stupid' rewrites of the initial 
code. I completely failed to recognize the 'for' loop as being Ruby 
code in the first place. Does Ruby really have an ++ operator? I missed 
that somehow. Damn. As embarrassingly illustrated by the fact that I 
coded my own ".increment" operator in the initial message instead of 
using it.

my_clues++