extract variable

Author: cmlchen

Diff for: src/lib_json/json_value.cpp

@@ -852,9 +852,11 @@ bool Value::asBool() const {
     return value_.int_ ? true : false;
   case uintValue:
     return value_.uint_ ? true : false;
-  case realValue:
-    // According to JavaScript language zero or NaN is regarded as false
-      return std::fpclassify(value_.real_) != FP_ZERO && std::fpclassify(value_.real_) != FP_NAN;
+  case realValue: {
+      // According to JavaScript language zero or NaN is regarded as false
+      const auto value_classification = std::fpclassify(value_.real_);
+      return value_classification != FP_ZERO && value_classification != FP_NAN;
+  }
   default:
     break;
   }