[pcp:master] reported: boolean / quantified operations for derived-metrics #github

[pcp:master] New Comment on Issue #270 boolean / quantified operations for derived-metrics ( https://github.com/performancecopilot/pcp/issues/270 )
By fche ( https://github.com/fche ) :

For defined(X) , maybe think about it as available(METRIC) ? VALUE : VALUE or default(METRIC,VALUE) , as a fetch-time-evaluated calculation for PM_ERR_NYI/AGAIN. If the METRIC is not available even in the PMNS, then it could const-propagate as a false into the expression tree and not be reevaluated later.