From: Morton Goldberg <m_goldberg@...>
Date: 2007-09-21T09:40:28+09:00
Subject: Re: Iterating through a file, sticking iterated array entries in

On Sep 20, 2007, at 11:41 AM, Peter Bailey wrote:

> I've got an array, a listing of "titles" in an xml file. Basically, I
> want to iterate through my file and, wherever I see the tag
> <registration>, I want to replace that with <subhead.4>code</ 
> subhead.4>,
> where "code" is the next entry in the stack of my array. Now, I've  
> tried
> this a number of ways and it does it, but, it doesn't cycle through my
> array entries. It populates all of my substitutions with just the  
> first
> entry in the array, none of the subsequent ones.
> ...
> $codes = []
> $codes = xmlfile.scan(/<issueList>\s*<issue +code *="[A-Z]{3}
> *">(.*?)<\/issue>\s*?/mi)
> ...
> $codes.each do |code|
> puts code
> xmlfile.gsub!(/<registration>?/,
> "<subhead.4>#{code}</subhead.4>/n<table>")
> end
>
> I'm getting the following. My "puts" statement, which is just there  
> for
> checking, does indeed list each entry of the array, though.
>
> <subhead.4>Trade (Domestic &amp; Foreign)</subhead.4>/n<table>
> which is correct, but, I'm getting it for all 115 occurrences of the
> <registration> tag.
>
> Maybe gsub isn't the way to do this. Obviously, I'm trying to iterate
> through every instance of <registration> and simply replace it with  
> the
> above code. Is gsub not an iteration tool?

The gsub! matches all the substitution targets on the first iteration  
of the 'each'; therefore, no matches occur on any subsequent  
iterations. Try something like:

<code>
source = <<TEXT
The quick brown
<fox> jumped over
the lazy <dog>
The quick brown
<fox> jumped over
the lazy <dog>
TEXT

codes = %w[a b c d e f g]
source.gsub!(/<(\w*)>/) { c = codes.shift; "<#{c}>#{$1}</#{c}>"}
puts source
</code>

<results>
The quick brown
<a>fox</a> jumped over
the lazy <b>dog</b>
The quick brown
<c>fox</c> jumped over
the lazy <d>dog</d>
</results>

Regards, Morton