puppetlabs-stdlib/lib/puppet/parser/functions/try_get_value.rb

module Puppet::Parser::Functions
  newfunction(
      :try_get_value,
      :type => :rvalue,
      :arity => -2,
      :doc => <<-eos
DEPRECATED: this function is deprecated, please use dig() instead.

Looks up into a complex structure of arrays and hashes and returns a value
or the default value if nothing was found.

Key can contain slashes to describe path components. The function will go down
the structure and try to extract the required value.

$data = {
  'a' => {
    'b' => [
      'b1',
      'b2',
      'b3',
    ]
  }
}

$value = try_get_value($data, 'a/b/2', 'not_found', '/')
=> $value = 'b3'

a -> first hash key
b -> second hash key
2 -> array index starting with 0

not_found -> (optional) will be returned if there is no value or the path did not match. Defaults to nil.
/ -> (optional) path delimiter. Defaults to '/'.

In addition to the required "key" argument, "try_get_value" accepts default
argument. It will be returned if no value was found or a path component is
missing. And the fourth argument can set a variable path separator.
  eos
  ) do |args|
    warning("try_get_value() DEPRECATED: this function is deprecated, please use dig() instead.")
    data = args[0]
    path = args[1] || ''
    default = args[2]

    if !(data.is_a?(Hash) || data.is_a?(Array)) || path == ''
      return default || data
    end

    separator = args[3] || '/'
    path = path.split(separator).map{ |key| key =~ /^\d+$/ ? key.to_i : key }
    function_dig([data, path, default])
  end
end