Value Key Language-Independent Type for YAML™ Version 1.1

Working Draft 2005-01-18

Oren Ben-Kiki

<oren@ben-kiki.org>

Clark Evans

<cce+yaml@clarkevans.com>

Brian Ingerson

<ingy@ttul.org>

This document may be freely copied provided it is not modified.

Status

This specification is a draft reflecting consensus reached by members of the yaml-core mailing list. Any questions regarding this draft should be raised on this list.

URI:

tag:yaml.org,2002:value

Shorthand:

!!value

Kind:

Scalar.

Canonical:

N/A (single format).

Regexp:

=

Definition:

Specify the default value of a mapping.

The “=” key is used to denote the "default value" of a mapping. In some cases, it is useful to evolve a schema so that a scalar value is replaced with a mapping. A processor may present a "scalar value" method that provides the value directly if the node is a scalar or returns the value of this key if the node is a mapping. If applications only access the scalar value through this interface then the schema may freely grow over time replacing scalar values with richer data constructs without breaking older processing systems.

Example 1. !!value Examples

---     # Old schema
link with:
  - library1.dll
  - library2.dll
---     # New schema
link with:
  - = : library1.dll
    version: 1.2
  - = : library2.dll
    version: 2.3