Puppet users - Apr 2013 - Defining custom resource types wrapping exec resources and using optional “unless”

The following code example is purely academical but it illustrates my 
question pretty well.

   define touch($file=$title, $unless=''/bin/false'') {
       exec { "/bin/touch ${file}": unless => $unless }
   }

If I define my own resource type that wraps another *exec* resource and I 
want to *add an optional "unless" condition* that I - if set - pass to
the
optional "unless" condiftion of *exec* - do I have to preset the field
with
''/bin/false''?

My understanding is that for each catalog run and all uses of this custom 
ressource type this resource''s unless check will then spawn a bash
process
running ''/bin/false'' if the unless field of "touch"
hasn''t been set .

What I actually intend is not to do any "unless" check at all if the
field
hasn''t been set - including calling "/bin/false".

Any thoughts? Thanks!

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On Wednesday, April 10, 2013 4:26:19 AM UTC-5, christian...@gmail.com
wrote:
>
> The following code example is purely academical but it illustrates my 
> question pretty well.
>
>    define touch($file=$title, $unless=''/bin/false'') {
>        exec { "/bin/touch ${file}": unless => $unless }
>    }
>
> If I define my own resource type that wraps another *exec* resource and I 
> want to *add an optional "unless" condition* that I - if set -
pass to
> the optional "unless" condiftion of *exec* - do I have to preset
the
> field with ''/bin/false''?
>
> My understanding is that for each catalog run and all uses of this custom 
> ressource type this resource''s unless check will then spawn a bash
process
> running ''/bin/false'' if the unless field of
"touch" hasn''t been set .
>
> What I actually intend is not to do any "unless" check at all if
the field
> hasn''t been set - including calling "/bin/false".
>
> Any thoughts? Thanks!
>
>
I think a parameter default of ''undef'' will probably achieve
what you want:

# note: the undef keyword must be unquoted
define touch($unless = undef) {
  exec { "/bin/touch ${title}": unless => $unless }
}

If that doesn''t work then you can use a testable dummy value for the 
parameter default, and use conditional code to declare the Exec without an 
''unless'' parameter when no explicit value is declared for the
defined-type
instance.


John

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Never heard of *undef *before - sounds great! Thanks

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