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= evalmimic

* http://github.com/tario/evalmimic

== DESCRIPTION:

 Evalmimic allow the implementation of eval like methods, solves the common problem of binding retrieve: in ruby you can't obtain the binding of the caller, or if you can, is some tricky

== INSTALL:

sudo gem install evalmimic

== USAGE

Use define_eval_method to add a eval like method to the class or as global function:

  class X
    define_eval_method :my_eval
    ...
  end

Define a method named internal_eval to handle the calls

  class X
    define_eval_method :my_eval

    def internal_eval(binding_, args)
       # binding_ is the original binding of the caller of my_eval
       # args is an array of the arguments passed to my_eval
    end
  end

Also, it can be use outside of a class, in analog way:

  define_eval_method :my_eval

  def internal_eval(binding_, args)
     # binding_ is the original binding of the caller of my_eval
     # args is an array of the arguments passed to my_eval
  end

=== Example 1

Creating your own implementation of eval

  require "rubygems"
  require "evalmimic"

  define_eval_method :my_eval

  def internal_eval(b_, args)
    b_.eval("a+b")
  end

  def foo
    a = 4
    b = 5

    my_eval
  end

  print foo,"\n"

=== Example 2

Creating an Evaluator class

  require "rubygems"
  require "evalmimic"

  class MyEvaluator
    define_eval_method :eval

    def internal_eval(b_, args)
      b_.eval(args[0])
    end

  end

  def foo
    m = MyEvaluator.new

    a = 4
    b = 5

    m.eval "a+b"

  end

  print foo,"\n"

=== Example 3

Hooking/monkey patching of the original eval

  require "rubygems"
  require "evalmimic"

  alias original_eval eval
  define_eval_method :eval

  def internal_eval(b_, args)
    print "eval called with code = #{args[0].inspect}\n"

    args[1] = args[1] || b_

    original_eval(*args)
  end

  def foo
    a = 4
    eval "a"
  end

  print foo,"\n"

== LICENSE:

Copyright (c) 2011 Roberto Dario Seminara <[email protected]>

evalhook is free software: you can redistribute it and/or modify
it under the terms of the gnu general public license as published by
the free software foundation, either version 3 of the license, or
(at your option) any later version.

evalhook is distributed in the hope that it will be useful,
but without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose.  see the
gnu general public license for more details.

you should have received a copy of the gnu general public license
along with evalhook.  if not, see <http://www.gnu.org/licenses/>.