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Fwd: [SOLUTION] Quiz #67 metakoans.rb

James Gray

2/19/2006 4:54:00 PM

Begin forwarded message:

> From: "Phil Tomson" <philtomson@gmail.com>
> Date: February 18, 2006 6:46:02 PM CST
> To: submission@rubyquiz.com
> Subject: [SOLUTION] Quiz #67 metakoans.rb
>
> James,
>
> Fun quiz!
>
> I don't subscribe to ruby-talk and the c.l.r bridge has been a bit
> flakey (I didn't see your original post for this quiz on c.l.r, only
> the responses) and I'll be out all day tomorrow.... so I include my
> solution below.
>
> Phil
>
> #knowledge.rb
> class Module
> def attribute(h_or_s, &b)
> if h_or_s.class == Hash
> str, val = h_or_s.keys[0].to_s, h_or_s.values[0]
> elsif h_or_s.class == String
> str, val = h_or_s.to_s, 0
> end
> if block_given?
> val = :init_block
> define_method(val, &b)
> end
> class_eval "def #{str}; @#{str}||=#{val} ; end"
> class_eval "def #{str}=(val); @#{str}=val; end"
> class_eval "def #{str}?; @#{str} ? true : false ; end"
> end
> end
1 Answer

Michael Q. Harris

2/19/2006 10:53:00 PM

0

The only interesting thing I have to say here that hasn't been said is
that this test seems like a variation of Pair Programming, where one
person writes the tests and the other writes the code. No better way
to ensure you only write code to make a failing test pass than to know
nothing about the problem space except the most recent test failure.

class Object
def attribute(arg, &block)
name = (arg.class == Hash ? arg.keys[0] : arg)
define_method(name) do
first_access_action(arg,&block) unless instance_eval("defined? "
+ "@" + name)
instance_variable_get "@" + name
end
attr_writer name
alias_method name+"?",name
end

def first_access_action(arg,&block)
name = (arg.class == Hash ? arg.keys[0] : arg)
send(name+"=",instance_eval(&block)) if block_given?
send(name+"=",arg.values[0]) if arg.class == Hash
end
end