Re: Re: How to make global variable with summary value

      Hello all, I know that is a very bad idea for cfengine but I
      want counting modifications by cfengine. I prepared small
      testing example:

I think your right this is a bad idea, but still can be a fun exercise
to read the policy....

,----
| bundle common success_add(value){
|   vars:
|       "sum"
|         string => eval("${sum} + ${value}", "math", "infix"),
|         if => isvariable("sum");
| 
|       "sum"
|         string => "${value}",
|         unless => isvariable("sum");
| 
|   reports:
|       "success: add=${value}, total=${sum}";
| }
| 
| bundle agent summary {
|   reports:
|       "SUMMARY: ${success_add.sum}";
| }
| 
| bundle agent __main__ {
|   methods:
|       "add_100" usebundle => success_add("100");
|       "add_010" usebundle => success_add("10");
|       "add_001" usebundle => success_add("1");
|       "summary";
| }
`----
Listing 1: Example Policy

      I expect SUMMARY=111 but i get very different result:

,----
| R: success: add=100, total=400.000000
| R: success: add=100, total=500.000000
| R: success: add=100, total=600.000000
| R: success: add=10, total=630.000000
| R: success: add=10, total=640.000000
| R: success: add=10, total=650.000000
| R: success: add=1, total=653.000000
| R: success: add=1, total=654.000000
| R: success: add=1, total=655.000000
| R: SUMMARY: 655.000000
`----

      OK, cfengine runs every bundle 3 times.

CFEngine will run each bundle in the `bundlesequence' and will take 3
passes in that bundle. But, a methods promise is only going to be called
once, that is to say `success_add(100)' isn't going to be run 3 times.

      Does there exist any solution to get the total value 111?

Seems with CFEngine, there is /almost/ always *a* way, here is one:

,----
| bundle common success_add(value, label){
|   vars:
|       "$(label)"
|         string => "$(value)",
|         meta => { "sum" };
| 
|       "_sum_vars" data => variablesmatching_as_data( "$(this.namespace):$(this.bundle)\..*", "sum" );
|       "sum" real => sum( getvalues( _sum_vars ) );
| 
|   reports:
|       "success: add=${value}, total=${sum}";
| 
| }
| 
| bundle agent summary {
|   reports:
|       "SUMMARY: ${success_add.sum}";
| }
| 
| bundle agent __main__ {
|   methods:
|       "add_100"
|         usebundle => success_add("100", "$(this.promiser)" );
|       "add_010"
|         usebundle => success_add("10", "$(this.promiser)");
|       "add_001"
|         usebundle => success_add("1", "$(this.promiser)");
|       "summary";
| }
`----
Listing 2: a way to get 111

,----
| R: success: add=100, total=100.000000
| R: success: add=10, total=110.000000
| R: success: add=1, total=111.000000
| R: SUMMARY: 111.000000
`----


      Why is the result 655 and not 666?

I don't want to mentally step through evaluation to count this up but
this is most likely related to pre-evaluation and multiple passes within
a given bundle.

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-- 
Nick Anderson | Doer of Things | (+1) 785-550-1767 | https://northern.tech

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