Mikhail Osher

testStr = "Hello Johny !";

function do_replace(inputStr, startWord, endWord, replaceStr)
  return string.gsub(inputStr, startWord .. " (%S+) " .. endWord, startWord .. " " .. replaceStr .. " " .. endWord);
end

result = do_replace(testStr, "Hello", "!", "habrahabr");
print(result);

<?php
/**
 * Some class
 *
 * @method static returntype methodname() comment
 * @method returntype methodname() comment
 */
?>