OOP palindrome checker example

word.php

<?php
/**
 * Class to create word objects.
 * Includes method to check whether word is a palindrome. Can be
 * extended with methods to check other properties of the word.
 *
 * @author James Roper <vadremix@gmail.com>
 */
class Word {
  protected $word_string;

  /**
   * Set object property
   *
   * @param string $word
   */
  public function __construct($word) {
    $prop['word'] = $word;

    // set properties, handles exception if any property is invalid
    try {
      $this->_set_properties($prop);
    } catch (Exception $e) {
      echo '<pre>Line '.$e->getTrace()[1]['line'].$e->getMessage() .'</pre>';
    }
  }

  /**
   * Sets objects properties.
   * By using a method for this, we can strictly validate input
   * to reduce potential for bugs.
   *
   * @param array $properties
   * @return boolean
   */
  protected function _set_properties($properties) {
    if(is_string($properties['word'])) {
      $this->word_string = $properties['word'];
    } else {
      throw new Exception(': new Word parameter should be a string.');
    }

    return true;
  }

  /**
   * Returns word as string
   *
   * @return string
   */
  public function get_word() {
    return $this->word_string;
  }

  /**
   * Checks whether object is a palindrome
   *
   * @return boolean
   */
  public function is_palindrome() {
    $word = $this->word_string;
    // converts string to array with 1 character chunks
    $word_array = str_split($word, 1);

    // declares variable to prepare for first loop iteration
    $word_reversed = '';

    // string is constructed in reverse by iterating forward
    // and appending each element to the beginning of a string
    foreach($word_array as $char) {
      $word_reversed = $char.$word_reversed;
    }

    // compares stings to determine if palindrome
    if($word_reversed == $word) {
      return true;
    } else {
      return false;
    }
  }
}

// Palindrome tests
$test[0] = new Word('cammac');
$test[1] = new Word('level');
$test[2] = new Word('bacon');
$test[3] = new Word(2112);

foreach($test as $i=>$current_test) {
  echo $current_test->is_palindrome() ? '<pre>Test '.($i+1).' is a palindrome.</pre>' : '<pre>Test '.($i+1).' is not a palindrome.</pre>';
}