From: "Peña, Botp" <botp@...>
Date: 2007-08-23T16:45:22+09:00
Subject: Re: Changing "self" for cleaner code

From: come [mailto:come.news@free.fr] 
# I ask that because I'm doing a program to access different unix os and
# I would like to write something like :
# with my_server do
#   ls("-lrt")
#   ps("-efl")
# end

is instance_eval ok for you?

irb(main):013:0> system "qri instance_eval"
--------------------------------------------------- Object#instance_eval
     obj.instance_eval(string [, filename [, lineno]] )   => obj
     obj.instance_eval {| | block }                       => obj
------------------------------------------------------------------------
     Evaluates a string containing Ruby source code, or the given
     block, within the context of the receiver (obj). In order to set
     the context, the variable self is set to obj while the code is
     executing, giving the code access to obj's instance variables. In
     the version of instance_eval that takes a String, the optional
     second and third parameters supply a filename and starting line
     number that are used when reporting compilation errors.

        class Klass
          def initialize
            @secret = 99
          end
        end
        k = Klass.new
        k.instance_eval { @secret }   #=> 99

=> true

some simple example,

irb(main):014:0> def with x, &block
irb(main):015:1>    x.instance_eval &block
irb(main):016:1> end
=> nil
irb(main):017:0> with "test" do
irb(main):018:1*   p length
irb(main):019:1>   p upcase
irb(main):020:1>   p capitalize
irb(main):021:1>   p self
irb(main):022:1> end
4
"TEST"
"Test"
"test"
=> nil
irb(main):023:0>

kind regards -botp