From: Brendan Stennett <brendan6@...>
Date: 2008-04-03T06:08:18+09:00
Subject: ruby constructor return value?

How do I alert an error if it occurs in an object's constructor?

Example:
Say im creating an object that relies on a give record from the database
zipcodes.

In php...
<?php
class Zip {
  private $zipcode;
  function __construct(zipcode) {
    //..code the looks up zipcode
    $numOfRecords = $mysqli->affected_rows;
    if ($numOfRecords == 0) {
      //this takes advantage of dynamically typed languages and passes a
boolean
      //value instead of the newly created object to the variables thats
being
      //assigned
      return false;
    } else {
      $this->zipcode = zipcode;
    }
  }
}

//then...
if ($o = new Zip('90210')) {
  //code if zipcode exists
} else {
  //code if it doesn't
}
?>

In ruby..
class Zip
  def initialize(zipcode)
    o = Zipcode.find_by_zipcode(zipcode)
    if o.length == 0
      return false
    else
      @zipcode = zipcode
    end
  end
end

//then...
if o = Zip.new('00000')
  //this block execute whether or not that zip code exists
else
  //never happens
end

..now i know there are easier ways to do this, but its just an example
to illustrate my point.
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