From: Bill Kelly <billk@...>
Date: 2006-04-12T03:02:48+09:00
Subject: Re: define_singleton_method(a_symbol,&block)

From: <ara.t.howard@noaa.gov>
>
> On Tue, 11 Apr 2006, Bill Kelly wrote:
> 
>> I was wondering what was the idiomatic way to do this:
>>
>> class BigDipper
>>   def little_dipper(a_symbol)
>>     define_singleton_method(a_symbol) {
>>       "#{a_symbol} is double-helix"
>>     }
>>   end
>> end
>> 
>> s_ = BigDipper.new
>> s_.little_dipper(:DNA)
>> s_.DNA
>>   => "DNA is a double-helix"
>>
>> q_ = BigDipper.new
>> q_.respond_to? :DNA
>>   => false
>
> 
> harp:~ > cat a.rb
> class BigDipper
>   def self.little_dipper(a_symbol)
>     define_method(a_symbol) { "#{a_symbol} is double-helix" }
>   end
>   def little_dipper(*a, &b) self.class.little_dipper(*a, &b) end
> end
> 
> s_ = BigDipper.new
> s_.little_dipper(:DNA)
> p s_.DNA

Thanks, Ara.  But is there any way to write it such that the
method is only added to the specific instance of the class?

I would like the following to return false:

> q_ = BigDipper.new
> p q_.respond_to?(:DNA)   # => false


Thanks,

Bill