Puppet users - Jun 2007 - test

I was wondering if there was an elegant way to extend a require array.

To whit it would be wonderful to do somthing like this:

class one {

  service { awesome:
    require   =>  [ File[one], File[two] ]
  }

  file {
    one:
      ...
    two:
      ...
  }
}

class two inherits one {
  Service[awesome] { Require => + [ File[three], File[four] ] }

  file {
    three:
      ...
    four:
      ...
  }
}

The idea being that class one is the base class for more than just class two
and there is a shared set of dependencies in class one that class two needs to
inherit and append to.

--Robert

Sorry about the subject line.  I was distracted when writing the first part of
the message.

--Robert

On Jun 12, 2007, at 5:29 PM, Robert Nickel wrote:
>
> class two inherits one {
>   Service[awesome] { Require => + [ File[three], File[four] ] }
[...]
> The idea being that class one is the base class for more than just  
> class two
> and there is a shared set of dependencies in class one that class  
> two needs to
> inherit and append to.
I''ve often envisioned this, although with this syntax:

   require +> [File[three], File[four]]

I have floated it once or twice to not-exactly-stellar reviews.

It should be pretty easy to add, and would be a great starter project  
for someone looking to contribute; it''d be restricted almost entirely  
to the parser.

  --
  The hypothalamus is one of the most important parts of the brain,
  involved in many kinds of motivation, among other functions. The
  hypothalamus controls the "Four F''s": 1. fighting;  2.
fleeing;
  3. feeding; and  4. mating.
                  -- Psychology professor in neuropsychology intro  
course
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com

I can say there are a number of things I''ve been thinking of using
puppet for that this would greatly simplify.

For example I have a very simplistic firewall define that takes an
array of ports,  I''d love to be able to simply extend the ports when
doing inheritance rather than redefining the whole array.

Thanks
Brian

On 6/12/07, Luke Kanies <luke@madstop.com> wrote:
> On Jun 12, 2007, at 5:29 PM, Robert Nickel wrote:
> >
> > class two inherits one {
> >   Service[awesome] { Require => + [ File[three], File[four] ] }
> [...]
> > The idea being that class one is the base class for more than just
> > class two
> > and there is a shared set of dependencies in class one that class
> > two needs to
> > inherit and append to.
>
> I''ve often envisioned this, although with this syntax:
>
>    require +> [File[three], File[four]]
>
> I have floated it once or twice to not-exactly-stellar reviews.
>
> It should be pretty easy to add, and would be a great starter project
> for someone looking to contribute; it''d be restricted almost
entirely
> to the parser.
>
>   --
>   The hypothalamus is one of the most important parts of the brain,
>   involved in many kinds of motivation, among other functions. The
>   hypothalamus controls the "Four F''s": 1. fighting;  2.
fleeing;
>   3. feeding; and  4. mating.
>                   -- Psychology professor in neuropsychology intro
> course
>   ---------------------------------------------------------------------
>   Luke Kanies | http://reductivelabs.com | http://madstop.com
>
>
> _______________________________________________
> Puppet-users mailing list
> Puppet-users@madstop.com
> https://mail.madstop.com/mailman/listinfo/puppet-users
>

On Tue, 2007-06-12 at 18:25 -0500, Luke Kanies wrote:
> I''ve often envisioned this, although with this syntax:
> 
>    require +> [File[three], File[four]]
It would be a great feature to have. The only bone I have with it is the
syntax: the immediately following feature request will be ''how do I
remove something from an array'' ? I think using
''->'' there is a little
odd. That would make using ''+='' and ''-=''
more natural, but then ''=>''
should become ''='' ...

Sorry, I don''t mean to start a flamewar (we did that already ;), but I
believe that if you have the ability to extend arrays, you should also
be able to remove elements from them (e.g., to have fewer ports on the
firewall open)

David

On Jun 15, 2007, at 11:19 PM, David Lutterkort wrote:
> On Tue, 2007-06-12 at 18:25 -0500, Luke Kanies wrote:
>> I''ve often envisioned this, although with this syntax:
>>
>>    require +> [File[three], File[four]]
>
> It would be a great feature to have. The only bone I have with it  
> is the
> syntax: the immediately following feature request will be ''how do
I
> remove something from an array'' ? I think using
''->'' there is a little
> odd. That would make using ''+='' and
''-='' more natural, but then ''=>''
> should become ''='' ...
>
> Sorry, I don''t mean to start a flamewar (we did that already ;),
but I
> believe that if you have the ability to extend arrays, you should also
> be able to remove elements from them (e.g., to have fewer ports on the
> firewall open)
"Should" and "can" are completely different.  I have a very
simple
pretty good syntax for adding to arrays, and I can easily see both  
the reasons for using it and how to implement it.

On the other hand, I do not nearly so clearly see a good syntax for  
removing from arrays, nor do I see good semantics around it.

Really, removing something from an array generally requires knowing  
exactly what''s in that array, which means that to provide this  
functionality we have to provide a bunch more.  With array addition,  
though, all you need to know is that you want this value added to the  
list, which doesn''t require any such understanding.

This "add to" syntax is mere hours of work, IMO, but any other  
syntaxes are probably days of work.

  --
  The major difference between a thing that might go wrong and a thing
  that cannot possibly go wrong is that when a thing that cannot  
possibly
  goes wrong goes wrong it usually turns out to be impossible to get at
  or repair.                           -- Douglas Adams, Mostly Harmless
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com