[ruby-talk:12654] Re: FEATURE REQUEST: 'my' local variables

> From: Stephen White [mailto:[e-mail]]
[...]
> > class Fred < String
> > def exec; self << self end
> > end
> 
> I don't understand how that causes a problem?
> 
> I'm an OOP newbie. Please be gentle. :)
and I am OOP wanebe ...
>
If I understand this part of your proposal correctly (note
I like your comments about do ... end versus {..} but don't
know if this would really re-solve all problems) behavior of 
your proposed syntax change by simply replacing also objects
``x'' with ``x.exec'' unless x is on the left hand side of an
assignment for example 

x = x + a 

is replaced by
   
x = x.exec + a.exec

In my example this would translated into 

  ``def exec ; self << self.exec end''

(To be true to your proposal one might even say that the 
return of any #exec call should be translated into 
def exec; do calculation; res.exec end)

The mere existence of such a stupid Object would cause the
interpreter to crash because as soon as the interpreter 
scans such an object the cataclysmic call to #exec would 
be initiated - right now such an object is harmless - 
unless you directly or indirectly call #exec - for
example in a simple assignment ``a = x'' this would
never happen.

This obviously very silly example is indicative that your
proposal has simply too many side effects especially when 
combined with self altering methods like #push, #reverse!, 
etc.. 
The beauty of something like #coerce is that it only springs
into acting for some methods and that you can integrate your 
own classes into ruby's build-in class system. In your example
it's as easy as 

-------------
$ ruby coerce.rb
Complex(-17.0, 2)
Complex(27, -2)
Complex(-2, 2.0)
10.0+0i
"12345hello"
12345hello
-------------
require 'Complex'
class Fred
     def initialize(var);@r = var end
     def coerce(l);  return @r.coerce(l) end
     def inspect; @r end
     def +(l); @r + l  end
     def -(l); @r - l end
end

a = Fred.new  Complex.new (3,2)

p  b = a -  20.0
p  c = 30 - a
p  d = Complex.new(1,4.0) - a
puts  b + c


a = Fred.new "12345"
p  b = a + "hello"
puts b
# and  c = "world" + a  would fail
# since String does not sport a #coerce

[...]
Christoph