add value_for_platform to DOC_CHANGES.md

1 files changed, 24 insertions, 0 deletions

diff --git a/DOC_CHANGES.md b/DOC_CHANGES.md
index 1a40d6730f..7ce531b3b5 100644
--- a/DOC_CHANGES.md
+++ b/DOC_CHANGES.md
@@ -6,6 +6,29 @@ Example Doc Change:
 Description of the required change.
 -->
 
+### value_for_platform Method
+
+- where <code>"platform"</code> can be a comma-separated list, each specifying a platform, such as Red Hat, openSUSE, or Fedora, <code>version</code> specifies the version of that platform, and <code>value</code> specifies the value that will be used if the node's platform matches the <code>value_for_platform</code> method. If each value only has a single platform, then the syntax is like the following:
++ where <code>platform</code> can be a comma-separated list, each specifying a platform, such as Red Hat, openSUSE, or Fedora, <code>version</code> specifies either the exact version of that platform, or a constraint to match the platform's version against. The following rules apply to constraint matches:
+
++ *  Exact matches take precedence no matter what, and should never throw exceptions.
++ *  Matching multiple constraints raises a <code>RuntimeError</code>.
++ *  The following constraints are allowed: <code><,<=,>,>=,~></code>.
++ 
++ The following is an example of using the method with constraints:
++ 
++ ```ruby
++ value_for_platform(
++   "os1" => {
++     "< 1.0" => "less than 1.0",
++     "~> 2.0" => "version 2.x",
++     ">= 3.0" => "version 3.0",
++     "3.0.1" => "3.0.1 will always use this value" }
++ )
++ ```
+
++ If each value only has a single platform, then the syntax is like the following:
+
 ### environment attribute to git provider
 
 Similar to other environment options:
@@ -29,6 +52,7 @@ Current documentation states:
 
 This is no longer correct as of 12.0. The `name` field is required; if
 it is not specified, an error will be raised if it is not specified.
+
 ### chef-zero port ranges
 
 - to avoid crashes, by default, Chef will now scan a port range and take the first available port from 8889-9999.