From: Randy Kramer <rhkramer@...>
Date: 2005-03-21T23:20:35+09:00
Subject: Re: Iterating through a string and removing leading characters

On Monday 21 March 2005 04:44 am, Robert Klemme wrote:
> Some remarks:
>
>  - The comparison between 5 and 6 does not seem fair, as you iterate in 6
> but not in 5.

Oops, for a minute I thought I had really screwed up (like by not doing 5 the 
10000 times).  AFAIK, I don't need to iterate (through the string) in 5 as 
the RE is not anchored to the beginning of the string--it still checks the 
entire string (line) for that pattern, which is what I try to achieve in 6 by 
the iteration through the string and check a character then invoke RE 
approach.  I am sure that my Ruby code to do that is not the best, and I may 
learn something by making it better, but I agree with your conclusion / 
recommendation (below) at least for the time being (although I do plan to 
play with str::scan and StringScanner at least a little bit (I presume they 
do similar things, but perhaps the 2nd is optimized somehow, particularly if 
I "require C" or whatever)).

>  - You don't use String#scan or #split which you are likely to need in
> practice, because  you want to sift through complete documents and want to
> treat all occurrences.

I need to let that sink in a bit.  In general I do want to treat all 
occurrences, but I plan to scan a line (actually a paragraph) at a time, and 
some things can only occur at the beginning of a line, so those would only be 
checked at the beginning of a line.

>  - The differences between the check-first-char approach and the pure RE
> approach are so insignificant that I'd not bother using the more complex
> code.  I'd stick with pure RE based approaches and only try to optimize if
> performance is bad.  (You mentioned premature optimization already... :-))

Thanks!  I pretty much agree at this time, although I want to play a little 
bit with StringScanner.

regards,
Randy Kramer