Issue #6621 has been updated by Stefan Schulte.
Puppet has undef as a special value. undef evaluates to false and it can be
used to unset defaults. I did a short test
<pre>
define test($var = undef) {
if $var {
notice "$name is true"
}
else {
notice "$name is false"
}
}
test { "empty string" : var => "" }
test { "unquoted nil" : var => nil }
test { "quoted nil" : var => "nil"}
test { "quoted undef" : var => "undef" }
test { "unquoted undef": }
</pre>
empty string and unquoted undef evaluate to false. If "" has to be true in your
use case, you can change `if $var` to `if $var != undef`
----------------------------------------
Feature #6621: Provide a nil type in the Puppet language
https://projects.puppetlabs.com/issues/6621
Author: Oliver Hookins
Status: Unreviewed
Priority: Normal
Assignee:
Category:
Target version:
Affected Puppet version: 2.6.5
Keywords:
Branch:
Currently there is no way to semantically convey the concept of nil, as Ruby
understands it.
nil currently evaluates to true and is internally converted to a string 'nil',
and '' evaluates (somewhat confusingly) to false. However, the empty string is
a permissible configuration value whereas nil inherently is not. Furthermore
non-empty strings evaluate to true unlike the empty string.
My use case, to put it very simply, is to work around some limitations of
communicating information between the external node classifier interface and
Puppet itself, since once you pass a nil value through the interface to Puppet,
nil loses its semantic value.
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