Extended maintenance of Ruby 1.9.3 ended on February 23, 2015. Read more

In Files

  • proc.c




Objects of class Binding encapsulate the execution context at some particular place in the code and retain this context for future use. The variables, methods, value of self, and possibly an iterator block that can be accessed in this context are all retained. Binding objects can be created using Kernel#binding, and are made available to the callback of Kernel#set_trace_func.

These binding objects can be passed as the second argument of the Kernel#eval method, establishing an environment for the evaluation.

class Demo
  def initialize(n)
    @secret = n
  def get_binding
    return binding()

k1 = Demo.new(99)
b1 = k1.get_binding
k2 = Demo.new(-3)
b2 = k2.get_binding

eval("@secret", b1)   #=> 99
eval("@secret", b2)   #=> -3
eval("@secret")       #=> nil

Binding objects have no class-specific methods.

Public Instance Methods

eval(string [, filename [,lineno]]) → obj click to toggle source

Evaluates the Ruby expression(s) in string, in the binding’s context. If the optional filename and lineno parameters are present, they will be used when reporting syntax errors.

def get_binding(param)
  return binding
b = get_binding("hello")
b.eval("param")   #=> "hello"
               static VALUE
bind_eval(int argc, VALUE *argv, VALUE bindval)
    VALUE args[4];

    rb_scan_args(argc, argv, "12", &args[0], &args[2], &args[3]);
    args[1] = bindval;
    return rb_f_eval(argc+1, args, Qnil /* self will be searched in eval */);

Commenting is here to help enhance the documentation. For example, code samples, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

If you want to help improve the Ruby documentation, please visit Documenting-ruby.org.