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Re: difference between class and object methods

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Sagy Drucker <sagysrael@gmail.com> writes:

> hello
> am i correct when i compare to java, and say:
> object methods in ruby are equivalent object methods in java
> and class methods in ruby are equivalent STATIC functions in java?

Instance methods in Ruby can be considered semantically equivalent to
instance methods in Java.

Ruby's class methods are quite different.  In Ruby, classes are
themselves objects that are available at runtime (yes, it's somewhat
circular), and so can have their own methods and variables.  Classes are
instances of the class Class (e.g. String.class == Class; this ties up at
the end, where Class.class == Class).

Java's static methods and variables are not class methods in the same
sense.  In Java, you cannot refer to 'super' in a static method, as
there is no 'this' (q.v. self, the current object; classes aren't objects in
Java.  In a Ruby class method, 'self', refers to the class object).
Since there is no this/self, static methods in Java cannot be overridden in
subclasses (although they can be replaced by a static method with the
same signature).  Being associated with a real object (the class), Ruby
class methods can be thought of as instance methods; they're just
methods on the class, not an individual instance of it.

Hope that helps.

Cheers,
Danny

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Thread

difference between class and object methods Sagy Drucker <sagysrael@gmail.com> - 2012-01-31 04:29 -0800
  Re: difference between class and object methods Robert Klemme <shortcutter@googlemail.com> - 2012-01-31 21:21 +0100
  Re: difference between class and object methods Rodrigo Kochenburger <divoxx@gmail.com> - 2012-02-01 07:41 -0800
  Re: difference between class and object methods Danny Woods <dannywoodz@yahoo.co.uk> - 2012-02-02 21:47 +0000
    Re: difference between class and object methods Alec Ross <alec@arlross.demon.co.uk> - 2012-02-03 11:51 +0000

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