From: Madsen <sen.zhang@126.com>
Date: 2005-11-06T22:57:11+09:00
Subject: Re: what does --can't define singleton method-- mean?

Daniel Sch�le wrote:

> irb(main):005:0> class << c
> irb(main):006:1> def angle
> irb(main):007:2> (arg/Math::PI)*180
> irb(main):008:2> end
> irb(main):009:1> end

Do you mean to add a method to an object?
This would work:
def c.angle
(arg/Math::PI)*180
end

I hope this will help.
> TypeError: can't define singleton method "angle" for Complex
>          from (irb):6
>          from :0
> irb(main):010:0> c.arg
> => 0.785398163397448
> irb(main):011:0> c.angle
> => 45.0
> irb(main):012:0>
>
> what does TypeError means here?
> can someone enlighten me
> I have one more related question
> I would like to have the angle method
> to return the angle in degrees for each
> Complex instance, how can I achieve it
> the obvious didn't work for me
>
> irb(main):014:0* class << Complex
> irb(main):015:1> def angle
> irb(main):016:2> (self.arg/Math::PI)*180
> irb(main):017:2> end
> irb(main):018:1> end
> => nil
> irb(main):019:0> d=Complex.new 1,1
> => Complex(1, 1)
> irb(main):020:0> d
> => Complex(1, 1)
> irb(main):021:0> d.arg
> => 0.785398163397448
> irb(main):022:0> d.angle
> => 0.785398163397448
> irb(main):023:0>
> 
> Regards, Daniel