Document ProcessedMetric class.

1 files changed, 21 insertions, 4 deletions

diff --git a/core/Plugin/ProcessedMetric.php b/core/Plugin/ProcessedMetric.php
index f70cc915d3..b2d563f633 100644
--- a/core/Plugin/ProcessedMetric.php
+++ b/core/Plugin/ProcessedMetric.php
@@ -11,7 +11,10 @@ use Piwik\DataTable;
 use Piwik\DataTable\Row;
 
 /**
- * TODO
+ * Base type for processed metrics. A processed metric is a metric that is computed using
+ * one or more other metrics.
+ *
+ * @api
  */
 abstract class ProcessedMetric extends Metric
 {
@@ -21,17 +24,31 @@ abstract class ProcessedMetric extends Metric
     const COMPONENT_SUBNAMESPACE = 'Metrics';
 
     /**
-     * TODO
+     * Computes the metric using the values in a {@link Piwik\DataTable\Row}.
+     *
+     * The computed value should be numerical and not formatted in any way. For example, for
+     * a percent value, `0.14` should be returned instead of `"14%"`.
+     *
+     * @return mixed
      */
     abstract public function compute(Row $row);
 
     /**
-     * TODO
+     * Returns the array of metrics that are necessary for computing this metric. The elements
+     * of the array are metric names.
+     *
+     * @return string[]
      */
     abstract public function getDependenctMetrics();
 
     /**
-     * TODO
+     * Executed before computing all processed metrics for a report. Implementers can return `false`
+     * to skip computing this metric.
+     *
+     * @param Report $report
+     * @param DataTable $table
+     * @return bool Return `true` to compute the metric for the table, `false` to skip computing
+     *              this metric.
      */
     public function beforeCompute(Report $report, DataTable $table)
     {