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From: Brian Candler <b.candler@pobox.com>
Newsgroups: comp.lang.ruby
Subject: Re: replace lines in a file using hash key-value pairs
Date: Fri, 20 May 2011 03:03:53 -0500
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.ruby:4800

Johan Martinez wrote in post #999809:
>   configfile = File.open("#{configfilename}","r+")
>
>   # read filelocations hash - for each key, replace with value
>   depprops.get_filelocations.each_pair do
>     |key,value|
>     puts " #{key} #{value}"
>     configfile.each do
>       |line|
>       puts line
>       # puts line if line.match("#{key}")
>       # line.sub!("/#{key}/","#{key} = #{value}")
>     end
>   end

These are nested loops. For the first key,value pair iteration, 
configfile.each goes through each of the lines. After that the file is 
exhausted, and .each won't do anything more. If you want to do that, you 
have to either .rewind or open the file again:

depprops.get_filelocations.each_pair do |key,value|
  File.open(configfilename) do |configfile|
    configfile.each_line do |line|
      ...
    end
  end
end

Using the block form of File.open ensures that it's closed after each 
iteration.

Of course, this is probably a very inefficient way to do what you want; 
I'd rather iterate through the file once, and for each line do the 
key/value substitutions. But then you get the results in a different 
order, of course.

> Also, is there any other way to implement search search-replace for all
> matching lines in a files based on hash/yaml file.

Probably the most efficient way is to build a single regex that matches 
all the substitutions in one go.

subs = {"hello"=>"goodbye", "world"=>"cruel life"}
keys = subs.keys.map { |k| Regexp.escape(k.to_s) }
pattern = Regexp.new("(?:#{keys.join("|")})")

lines = "hello world\ntesting\nhello again hello\n"
lines.each_line do |line|
  puts line.gsub(pattern) { |k| subs[k] }
end

-- 
Posted via http://www.ruby-forum.com/.