a fork of https://github.com/puppetlabs/puppetlabs-stdlib/blob/master/lib/puppet/parser/functions/concat.rb making the append behaviour more explicit

append.rb

#
# concat.rb
#

module Puppet::Parser::Functions
  newfunction(:append, :type => :lvalue, :doc => <<-EOS
Appends the contents of array 2 onto array 1.

*Example:*

    $foo = [ '1', '2', '3' ]
    append($foo, ['4','5','6'])

Would result in $foo having the value:

  ['1','2','3','4','5','6']
    EOS
  ) do |arguments|

    # Check that 2 arguments have been given ...
    raise(Puppet::ParseError, "append(): Wrong number of arguments " +
      "given (#{arguments.size} for 2)") if arguments.size != 2

    a = arguments[0]
    b = arguments[1]

    # Check that both args are arrays.
    unless a.is_a?(Array) and b.is_a?(Array)
      raise(Puppet::ParseError, 'append(): Requires arrays to work with')
    end

    a.concat(b)
  end
end