From: Robert Klemme <shortcutter@...>
Date: 2007-06-06T21:15:04+09:00
Subject: Re: concept of self

On 06.06.2007 12:57, dblack@wobblini.net wrote:
> Hi --
> 
> On Wed, 6 Jun 2007, Robert Klemme wrote:
> 
>> On 06.06.2007 03:24, Daniel Waite wrote:
>>> What I got most from it was its *incredibly thorough* explanation of 
>>> the concept of 'self' in Ruby. Moments after finishing the chapter on 
>>> self I ran to _why's creature code and, line by line, explained 
>>> exactly what it was doing. I was so proud of myself. :)
>>
>> You make it sound as if there was something complex about "self".  
>> Makes me wonder whether I am missing something about "self".  As far 
>> as I can see "self" is an ordinary variable with these additional 
>> properties:
>>
>> - it is automatically set to the current receiver and it cannot be 
>> altered by Ruby code
>>
>> - it is implicitly used for method invocations without an explicit 
>> receiver and for instance variable access
>>
>> Did I miss anything?
> 
> Only the fact that in practice, grasping self is a stumbling-block for
> a lot of people.  In addition to just getting the concept of a
> "default object", which is not always easy, there's the question of
> where and when self changes, which can be confusing because it
> sometimes overlaps with local scope but not always.

This reminds me of the headaches I had when confronted with OOP the 
first time.  That's quite a few years ago now and OOP has become my 
second nature (or so) - that's probably the reason why I did not find 
anything strange about "self".  But true, for somebody relatively new to 
OOP this might be considerably harder.  I had forgotten that.  But it's 
good to be reminded of this once in a while.

> So I wanted to explain (and document and demonstrate) both self and
> scope pretty thoroughly.  Almost anything in the language can probably
> be reduced to a couple of defining phrases, but just saying (for
> example) that a class method is a singleton method of a class object
> doesn't actually make everyone understand or feel confident about
> applying the concepts involved.  People really do learn in different
> ways :-)

Sure.  I didn't want to question the explanation (haven't even read the 
book as I am not doing any Rails), I was just curious whether I missed 
something.  Thank you for your explanation!

Kind regards

	robert