From: Jeremy Bopp <jeremy@...>
Date: 2010-09-18T11:43:19+09:00
Subject: Re: search and replace

On 09/17/2010 07:51 PM, John Smith wrote:
> Jeremy Bopp wrote:
>> On 9/17/2010 2:02 PM, John Smith wrote:
>>> Hi everyone,
>>>
>>> I want to be able to run a program that will do a bunch
>>> of searches specified in an array of strings, and replace the
>>> first occurrence of those strings with strings specified on a
>>> second array for a given text file.
>>>
>>> What would be the best way to do this?
>>
>> Maybe something like this:
>>
>> changes = [
>>   ['string1', 'replacement1'],
>>   ['string2', 'replacement2'],
>>   ...
>> ]
>>
>> File.open('somefile') do |f|
>>   f.each do |line|
>>     line_changed = false
>>     changes.each do |search, replacement|
>>       if line.sub!(search, replacement) then
>>         line_changed = true
>>         puts line
>>         break
>>       end
>>     end
>>     puts line unless line_changed
>>   end
>> end
>>
>>
>> -Jeremy
> 
> That one almost works but it needs to do the
> replacement only the first occurrence. What's
> the easiest way to fix it to do that. I'm thinking of
> a 'detect' but I'm not sure where I'd put it.
>

I'm not sure what you mean by only replacing the first occurrence.  Are
you saying that there could be more than 1 line in the file which could
match a given search string but that you only want the first one of
those to be processed?  Maybe you could give a trivial example of some
kind showing what you have and what you want to get.

-Jeremy