# Programming Ruby ### The Pragmatic Programmer's Guide
Previous < | Contents ^ | Next >

class Binding |
Parent: | Object
Version: | 1.6

### Index:

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`
`end`
`def getBinding`
`return binding()`
`end`
`end`
``
`k1 = Demo.new(99)`
`b1 = k1.getBinding`
`k2 = Demo.new(-3)`
`b2 = k2.getBinding`
``
`eval("@secret", b1)` | » | `99`
`eval("@secret", b2)` | » | `-3`
`eval("@secret")` | » | `nil`

Binding objects have no class-specific methods.

Previous < | Contents ^ | Next >

Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2001 by Addison Wesley Longman, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/)).

Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder.

Distribution of the work or derivative of the work in any standard (paper) book form is prohibited unless prior permission is obtained from the copyright holder.