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copied!<p>I use ruby 1.9.2.</p> <p><code>gsub</code>/<code>scan</code> iterate over matches to a given regex/string, and is used in three ways:</p> <ol> <li>If <code>scan</code> is used without a block, it returns an array of matches.</li> <li>If <code>scan</code> is used with a block, it iterates over matches and performs something.</li> <li>If <code>gsub</code> is used, it replaces the matches with what is given as the second argument or as the block, and returns a string.</li> </ol> <p>On the other hand, there is <code>split</code> that matches the complement of what <code>gsub</code>/<code>scan</code> match. However, there is only one way to use this:</p> <ol> <li>If <code>split</code> is used without a block, It returns an array of the complement of the matches.</li> </ol> <p>I wanted the other two missing usages related to <code>split</code>, and tried to implement them. The following <code>every_other</code> extends <code>split</code> so that it can be used like <code>scan</code>.</p> <pre><code>class String def every_other arg, &pr pr ? split(arg).to_enum.each{|e| pr.call(e)} : split(arg) end end # usage: 'cat, two dogs, horse, three cows'.every_other(/,\s*/) #=> array 'cat, two dogs, horse, three cows'.every_other(/,\s*/){|s| p s} # => executes the block </code></pre> <p>Then, I tried to implement the counterpart of <code>gsub</code>, but cannot do it well.</p> <pre><code>class String def gsub_other arg, rep = nil, &pr gsub(/.*?(?=#{arg}|\z)/, *rep, &pr) end end # usage 'cat, two dogs, horse, three cows'.gsub_other(/,\s*/, '[\1]') # or 'cat, two dogs, horse, three cows'.gsub_other(/,\s*/) {|s| "[#{s}]"} # Expected => "[cat], [two dogs], [horse], [three cows]" # Actual output => "[cat][],[ two dogs][],[ horse][],[ three cows][]" </code></pre> <ul> <li>What am I doing wrong?</li> <li>Is this approach correct? Is there a better way to do it, or are there already methods that do this?</li> <li>Do you have suggestions about the method names?</li> </ul>

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