Puppet users - Sep 2012 - custom function, setvar and variable scoping

Hello,

I''m trying to make a set of functions to simulate an array with which I
would be able to append value in the same scope.

The first function is called "array_append" which take 2 arguments:
the
variable name and the value to append. The function then iterates through 
variables "#{name}_#{i}" (with incrementing i from 0) until the
variable
does not exists and then set the value of this variable. This way I''m
using
one variable for each element of my array and I can simulate a real array 
from the puppet DSL.

Here''s the function I''ve made:

module Puppet::Parser::Functions
  newfunction(:array_append) do |args|
    i = 0
    i += 1 while lookupvar("#{args[0]}_#{i}")
    puts "I''ve set #{args[0]}_#{i} to #{args[1]}"
    setvar("#{args[0]}_#{i}", args[1])
  end
end


If I''m calling this function from a manifest it works as expected:
test.pp

array_append("toto", "prout0")
array_append("toto", "prout1")
array_append("toto", "prout2")


#puppet agent test.pp

I''ve set toto_0 to prout0
I''ve set toto_1 to prout1
I''ve set toto_2 to prout2
Finished catalog run in 0.02 seconds


But if I want to set a global variable it does not work anymore and
I''ve
errors. It seams that 

test2.pp:

array_append("::toto", "prout0")
array_append("::toto", "prout1")
array_append("::toto", "prout2")


#puppet agent test2.pp

I''ve set ::toto_0 to prout0
I''ve set ::toto_0 to prout1
Error: Cannot reassign variable ::toto_0 at 
/root/puppet/manifests/test.pp:9 on node www1.egasys.com
Error: Cannot reassign variable ::toto_0 at 
/root/puppet/manifests/test.pp:9 on node www1.egasys.com


Then if I''m calling array_append from a module defined resource:

test3.pp

network::route::add_net {"42.42.42.0/24": gw =>
"192.168.0.1"}
network::route::add_net {"54.54.54.0/24": gw =>
"192.168.0.1"}


modules/network/manifests/route/add_net.pp

define network::route::add_net($gw) {
  array_append("::routes_net", {name => $name, gw => $gw})
}


#puppet agent test3.pp
I''ve set ::routes_net_0 to name42.42.42.0/24gw192.168.0.1
I''ve set ::routes_net_0 to name54.54.54.0/24gw192.168.0.1

this time: no errors but setvar is not working: it''s like setvar does 
nothing

I can''t understand why case #2 and #3 are not working and if
it''s a normal
behaviour or a bug.

if you have any ideas ?

thx for your help

++ Jerome

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On Saturday, September 29, 2012 8:10:43 AM UTC-5, Jérôme Loyet
wrote:
>
> Hello,
>
> I''m trying to make a set of functions to simulate an array with
which I
> would be able to append value in the same scope.
>
> The first function is called "array_append" which take 2
arguments: the
> variable name and the value to append. The function then iterates through 
> variables "#{name}_#{i}" (with incrementing i from 0) until the
variable
> does not exists and then set the value of this variable. This way
I''m using
> one variable for each element of my array and I can simulate a real array 
> from the puppet DSL.
>
> Here''s the function I''ve made:
>
> module Puppet::Parser::Functions
>   newfunction(:array_append) do |args|
>     i = 0
>     i += 1 while lookupvar("#{args[0]}_#{i}")
>     puts "I''ve set #{args[0]}_#{i} to #{args[1]}"
>     setvar("#{args[0]}_#{i}", args[1])
>   end
> end
>
>
> If I''m calling this function from a manifest it works as expected:
> test.pp
>
> array_append("toto", "prout0")
> array_append("toto", "prout1")
> array_append("toto", "prout2")
>
>
> #puppet agent test.pp
>
> I''ve set toto_0 to prout0
> I''ve set toto_1 to prout1
> I''ve set toto_2 to prout2
> Finished catalog run in 0.02 seconds
>
>
> But if I want to set a global variable it does not work anymore and
I''ve
> errors. It seams that 
>
> test2.pp:
>
> array_append("::toto", "prout0")
> array_append("::toto", "prout1")
> array_append("::toto", "prout2")
>
>
> #puppet agent test2.pp
>
> I''ve set ::toto_0 to prout0
> I''ve set ::toto_0 to prout1
> Error: Cannot reassign variable ::toto_0 at 
> /root/puppet/manifests/test.pp:9 on node www1.egasys.com
> Error: Cannot reassign variable ::toto_0 at 
> /root/puppet/manifests/test.pp:9 on node www1.egasys.com
>
>
> Then if I''m calling array_append from a module defined resource:
>
> test3.pp
>
> network::route::add_net {"42.42.42.0/24": gw =>
"192.168.0.1"}
> network::route::add_net {"54.54.54.0/24": gw =>
"192.168.0.1"}
>
>
> modules/network/manifests/route/add_net.pp
>
> define network::route::add_net($gw) {
>   array_append("::routes_net", {name => $name, gw => $gw})
> }
>
>
> #puppet agent test3.pp
> I''ve set ::routes_net_0 to name42.42.42.0/24gw192.168.0.1
> I''ve set ::routes_net_0 to name54.54.54.0/24gw192.168.0.1
>
> this time: no errors but setvar is not working: it''s like setvar
does
> nothing
>
> I can''t understand why case #2 and #3 are not working and if
it''s a normal
> behaviour or a bug.
>
> if you have any ideas ?
>
>
My guess would be that setvar() is attempting to use the full string you 
supplied as a simple variable name, instead of resolving it as a qualified 
name.  That would make sense because setvar() probably itself resolves to 
or wraps scope.setvar(), where ''scope'' is the scope object
representing the
current namespace scope.

It may be possible to find and use the scope object for the scope you want, 
but it would be all-around better to avoid attempting to modify a different 
scope than the one in which the function call appears.


John

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