From: "Simon Kröger" <SimonKroeger@...>
Date: 2005-08-09T06:55:53+09:00
Subject: Re: polymorphism and/or named parameters: the ruby way?

Joel VanderWerf wrote:

> Simon Kr�ger wrote:
> 
>>>>This very useful little method is a nice thing to have in your
>>>>bag-o-tricks.
>>>
>>>
>>>Nice. you could even call it #then:
>>>
>>>class Object
>>>  def then
>>>    yield(self)
>>>    self
>>>  end
>>>end
>>>
>>>#Then you could do these types of things:
>>>a = (0..10).to_a
>>>i = 3
>>>p a[i.then{i+=1}]
>>>p i
>>>
>>>[..snip..]
>>
>>
>>But be carefull:
>>
>>i = 3
>>p i.then{i+=1}
>>p i
>>
>>i = [3]
>>p i.then{i << 4}
>>p i
>>
>>
>>output:
>>3
>>4
>>[3, 4]
>>[3, 4]
>>
>>
>>(perhaps this was obvious to all, except me)
>>
>>cheers
>>
>>Simon
> 
> 
> Good point. You really have to be especially clear about whether you are
>  modifying a variable binding or an object.
> 
> i = [3]
> p i.then{i+=[4]}   # ==> [3]
> p i                # ==> [3, 4]
> 

woohoo,
i+=[4] creates a new array, right?!

this is - lets say - 'suboptimal' in terms of speed for the
99.9% of cases where you do not need the old array.
(ok, you should realy use <<, except if you use 'then' -
I would not like to teach someone this)

cheers

Simon