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I'm going through a module that manages network, in order to understand how puppet modules work, what I'm stuck on is understanding what $::nisdomainname is, where did it come from and what does "$::" mean and why is the nisdomain portion outside the define block? An excerpt from a file in the module is below, can someone help me with the understanding?

define network::global (
  $hostnamemod = '',
  $gateway = '',
  $vlan = '',
  $nozeroconf = '',
  $gatewaydev = ''
) {
  $nisdomain = $::nisdomainname ? {
    ''      => '',
    default => $::nisdomainname,

Thanks in advance Dan

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up vote 1 down vote accepted

In puppet 3.0 and newer, scoping rules will change and you can no longer use $variablename to refer to a variable in global scope, the correct syntax is $::variablename. This syntax also works in 2.7, and maybe in older versions too.

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ahh thanks, but then why wouldn't the other variables like "hostnamemod" also be set as $::hostnamemod = ''? – Dan Feb 6 '13 at 13:01
Because those are parameters to your define, not references to variables in global scope. – Dennis Kaarsemaker Feb 6 '13 at 13:02
ok cleared it up now. Appreciate it. – Dan Feb 6 '13 at 13:07
One final point, if I may. does the nisdomainname check state, that if the nisdomainname is empty set it to empty otherwise default to setting it to the $::nisdomainname. Which if not defined would be empty, am I right? – Dan Feb 6 '13 at 13:07
@DennisKaarsemaker It's not a requirement in 3.0 to specify top scope explicitly. The changes in 3.0 affect dynamic scope only. – Shane Madden Feb 7 '13 at 4:44

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