From: Brian Candler <b.candler@...>
Date: 2011-08-02T22:04:41+09:00
Subject: Re: Numeric#coerce docs are a disaster

Roughly speaking: if 'a' is a numeric type, and ruby doesn't know how to 
make

    a.+(b)

work (where '+' can be any binary math operator), then it calls 
b.coerce(a) and repeats the operation on the returned pair of values.


>> 1 + "2"
TypeError: String can't be coerced into Fixnum
  from (irb):1:in `+'
  from (irb):1
  from :0
>> class String; def coerce(other); [other, self.to_f]; end; end
=> nil
>> 1 + "2"
=> 3.0
>> 1 - "2"
=> -1.0

-- 
Posted via http://www.ruby-forum.com/.