Puppet Function: pick_default

Defined in:
puppet/modules/stdlib/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) 


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# File 'puppet/modules/stdlib/lib/puppet/parser/functions/pick_default.rb', line 2

newfunction(:pick_default, :type => :rvalue, :doc => <<-EOS

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.

EOS
) do |args|
  fail "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