Test if value is instance of \Closure

framework/grid/DataColumn.php

@@ -141,11 +141,11 @@ class DataColumn extends Column
 	protected function renderDataCellContent($model, $key, $index)
 	{
 		if ($this->value !== null) {
-		if (is_callable($this->value)) {
-			$value = call_user_func($this->value, $model, $index, $this);
-		} else {
-			$value = ArrayHelper::getValue($model, $this->value);
-		}
+			if ($this->value instanceof \Closure) {
+				$value = call_user_func($this->value, $model, $index, $this);
+			} else {
+				$value = ArrayHelper::getValue($model, $this->value);
+			}
 		} elseif ($this->content === null && $this->attribute !== null) {
 			$value = ArrayHelper::getValue($model, $this->attribute);
 		} else {