Puppet Function: pick_default

Defined in:
lib/puppet/parser/functions/pick_default.rb
Function type:
Ruby 3.x API

Overview

pick_default() ⇒ Any

This function is similar to a coalesce function in SQL in that it will return the first value in a list of values that is not undefined or an empty string (two things in Puppet that will return a boolean false value). If no value is found, it will return the last argument.

Typically, this function is used to check for a value in the Puppet Dashboard/Enterprise Console, and failover to a default value like the following:

$real_jenkins_version = pick_default($::jenkins_version, '1.449')

The value of $real_jenkins_version will first look for a top-scope variable called ‘jenkins_version’ (note that parameters set in the Puppet Dashboard/ Enterprise Console are brought into Puppet as top-scope variables), and, failing that, will use a default value of 1.449.

Note that, contrary to the pick() function, the pick_default does not fail if all arguments are empty. This allows pick_default to use an empty value as default.

Returns:

  • (Any) 


5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
 
# File 'lib/puppet/parser/functions/pick_default.rb', line 5

newfunction(:pick_default, :type => :rvalue, :doc => <<-DOC
  This function is similar to a coalesce function in SQL in that it will return
  the first value in a list of values that is not undefined or an empty string
  (two things in Puppet that will return a boolean false value). If no value is
  found, it will return the last argument.

  Typically, this function is used to check for a value in the Puppet
  Dashboard/Enterprise Console, and failover to a default value like the
  following:

    $real_jenkins_version = pick_default($::jenkins_version, '1.449')

  The value of $real_jenkins_version will first look for a top-scope variable
  called 'jenkins_version' (note that parameters set in the Puppet Dashboard/
  Enterprise Console are brought into Puppet as top-scope variables), and,
  failing that, will use a default value of 1.449.

  Note that, contrary to the pick() function, the pick_default does not fail if
  all arguments are empty. This allows pick_default to use an empty value as
  default.
DOC
           ) do |args|
  raise 'Must receive at least one argument.' if args.empty?
  default = args.last
  args = args[0..-2].compact
  args.delete(:undef)
  args.delete(:undefined)
  args.delete('')
  args << default
  return args[0]
end