From: Kyle Schmitt <kyleaschmitt@...>
Date: 2008-09-26T04:30:15+09:00
Subject: Re: Getting the right class with inheritance and super()

On Thu, Sep 25, 2008 at 1:31 PM, Robert Klemme
<shortcutter@googlemail.com> wrote:
> 2008/9/25 Kyle Schmitt <kyleaschmitt@gmail.com>:
>> Reading the example you gave, and even some on the net, it looks like
>> I'd need the Array class to have a coerce method that can change an
>> Array into a FixedSizeArray?
>
> No.  Your coerce method needs to take care.  Look at my example.  I
> did not change Fixnum or Float.
Right, you didn't change it, but in the example you're calling coerce
on whatever it is that's passed in (perhaps this is the source of my
confusion):

Class X
... most everything removed ...
 def + other
   if self.class === other
     # fake only
     self.class.new
   else
     #only going to get here if other isn't of class X
     a, b = other.coerce(self)
     #doesn't whatever class other is have to have a coerce method?
     a + b
   end
 end
end


Now if we pull up irb.
fixnum=10
float=11.0
hash={}
array=[]
string="Wax Rabbits"

fixnum.respond_to?"coerce"
=> true
float.respond_to?"coerce"
=> true
hash.respond_to?"coerce"
=> false
array.respond_to?"coerce"
=> false
string.respond_to?"coerce"
=> false

So since Arrays Hashes and Strings don't have a coerce, does that mean
they can't be used in this fashion?

> That's ok but that does not mean that a FixedSizedArray *is an* Array.
>  I was talking about semantics of inheritance which is usually denoted
> *is a* relationship.
>
> Cheers
>
> robert

Thanks
--Kyle