---
title: Adding Quality
toc: false
...

> Back to [Intro]()

The customer is interested in non-functional qualities, such as, `productivity`, `cost`, `batterylife`, and `security`. Bob creates an abstract clafer with these quality attributes.

```clafer
abstract Feature
    productivity -> integer
    cost -> integer
    batterylife -> integer
    security -> integer
```

Features that contribute to variant quality extend the `Feature`:

```clafer
abstract MobilePhone
    Connectivity : Feature
        [ batterylife = -12]
        [ productivity = 14]
        [ security = 43]
        [ cost = 101]        
        xor Bluetooth
            Bluetooth20EDR : Feature
                [ batterylife = -4]
                [ productivity = 1]
                [ security = -15]
                [ cost = 1]
            Bluetooth21EDR : Feature
                [ batterylife = -2]
                [ productivity = 4]
                [ security = -10]
                [ cost = 1]
            Bluetooth40 : Feature
                [ batterylife = -1]
                [ productivity = 16]
                [ security = -2]
                [ cost = 2]
        GSM : Feature
            [ batterylife = -2]
            [ productivity = 2]
            [ security = -10]
            [ cost = 1]
        LTE : Feature ?
            [ batterylife = -1]
            [ productivity = 16]
            [ security = -3]
            [ cost = 3]
        WiFi: Feature ?
            [ batterylife = -10]
            [ productivity = 20]
            [ security = -15]
            [ cost = 20]
        USB : Feature ?
            [ batterylife = 10]
            [ productivity = 20]
            [ security = 0]
            [ cost = 3]
    xor Battery
        LiBattery1150 : Feature
            [ batterylife = 60]
            [ productivity = 0]
            [ security = 0]
            [ cost = 10]
        LiBattery1400 : Feature
            [ batterylife = 70]
            [ productivity = 0]
            [ security = 0]
            [ cost = 15]

    total_productivity -> integer = sum Feature.productivity
    total_batterylife -> integer = sum Feature.batterylife
    total_security -> integer = sum Feature.security
    total_cost -> integer = sum Feature.cost
```

Stating optimization objectives:

```clafer
<< max OptimalPhone.total_batterylife >>
<< max OptimalPhone.total_productivity >>
<< max OptimalPhone.total_security >>
<< min OptimalPhone.total_cost >>
```

Defining an optimal variant:

```clafer
OptimalPhone : MobilePhone
```

```{.clafer .mooviz}
```

```{.clafer .links}
```