documentation.ruby-from-other-languages.to-ruby-from-php.textile

PHP is in widespread use for web applications, but if you want to use Ruby on Rails
or just want a language that’s more tailored for general use, Ruby is worth a look.

Similarities

As in PHP, in Ruby…

• Ruby is dynamically typed, like in PHP, so you don’t need to worry about having to
  declare variables.
• There are classes, and you can control access to them like in PHP 5 (public,
  protected and private)
• Some variables start with $, like in PHP (but not all)
• There’s eval, too.
• You can use string interpolating. Instead of doing “$foo is a $bar”, you can do
  “#{foo} is a #{bar}” — like in PHP, this doesn’t apply for single-quoted strings.
• There’s heredocs
• Ruby has exceptions, like PHP 5
• There’s a fairly large standard library
• Arrays and hashes work like expected, if you exchange array() for { and }:
  array('a' => 'b') becomes {'a' => 'b'}.
• true and false behave like in PHP, but null is called nil

Differences

Unlike in PHP, in Ruby…

• There’s strong typing. You’ll need to call to_s, to_i etc. to convert between
  strings, integers and so on, instead of relying on the language to do it
• Strings, numbers, arrays, hashes, etc. are objects. Instead of calling abs(-1)
  it’s -1.abs
• Parentheses are optional in method calls, except to clarify which parameters go to
  which method calls
• Instead of naming conventions, like underscores, the standard library and extensions
  are organized in modules and classes
• Reflection is an inherent capability of objects, you don’t need to use Reflection
  classes like in PHP 5
• Variables are references.
• There’s no abstract classes or interfaces
• Hashes and arrays are not interchangeable
• Only false and nil are false: 0, array() and "" are all true in conditionals.
• Almost everything is a method call, even raise (throw in PHP).