From: gabriele renzi <surrender_it@...1.vip.ukl.yahoo.com>
Date: 2004-01-19T08:15:04+09:00
Subject: Re: setting instance variable "dynamically"

il Sun, 18 Jan 2004 18:26:22 +0100, Bauduin Raphael <rb@raphinou.com>
ha scritto::

>I saw in the pickaxe there's a way to call methods dynamically, with
>send("method_name"):
>
>"test".send("length")  # 4
>
>What I want to do is set a variable this way. Is it possible?
>
>I'm working on a translation tool for a website. rows returned
>are of the form:
>["id", "language", "value"]
>
>the value of the language field is the identical to the member variable
>that will contain the row (wrapped in an object actually).
>
>I thought of something like this:
>
>class Term
>attr :query, :fr, :nl, :en
>     def initialize(dbh, id)
>         @query = "select * from translations where id='#{id}'"
>         dbh.select_all(query) do |row|
>             self.send(row[1].to_s)=Translation.new(row)
>         end
>     end
>     def get_french()
>         @fr.value
>     end
>end
>
>But that isn't accepted.
>Does anyone have the solution?

>> class C
>>  def initialize
>>   @a,@b=10,20
>>  end
>> end
=> nil
>> ary=['a','b']
=> ["a", "b"]
>> c=C.new
=> #<C:0x2810628 @b=20, @a=10>
>> c.send("a",10)
NoMethodError: undefined method `a' for #<C:0x2810628 @b=20, @a=10>
        from (irb):8:in `send'
        from (irb):8
>> class C
>>  def initialize
>>   @a,@b=10,20
>>  end
>> attr_accessor :a, :b
>> end
=> nil
>> c.send("a",10)
ArgumentError: wrong number of arguments(1 for 0)
        from (irb):15:in `a'
        from (irb):15:in `send'
        from (irb):15
>> c.send("a"+"=",10)
=> 10
>> c.a
=> 10


you may even use instance_eval("@a="+value.to_s)