Info2: Exercise 01: Application Design

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Learning Goals

After this lab you should be able to agree with each of the following statements.

I can use CRC Cards to design an application:

Using the underline methods, I can identify candidates for classes, methods and fields.
By working through scenarios I can identify cases where a class needs to be split up.
By working through scenarios I can identify cases where classes need to be merged.
By working through scenarios I can identify cases where additional classes need to be added.
By working through scenarios I can identify what data needs to be stored.

Pre-Lab

Remember to do all the necessary steps listed on the Labs page, including the following exercises:

P1. Refamiliarize yourself with the Zuul Project in Info1.

P2. Recall the Responsibilities of the given classes. What was the point of the refactoring(s)?

P3. Find out what the Class-Responsibility-Collaboration Card method is, what the use of CRC Cards is and how they are created. The following resources can be of help:

P4. For the bored or curious: Check out TubMud

Assignment: CRC Cards

1. Background and Requirements

A Startup had found the Zuul Example and decided to make a cool real multi-user dungeon game based on it. You’ve been hired to do the programming, and there have been several meetings to talk about what should be added to the simple Zuul Project. The outcome is a description about the desired functionality. (We won’t be concerned with how that happens in detail, this is called Requirements Engineering and will be discussed in the third semester in Info3.)

Assume that this is the description written:
(this is a lot, read through all of it, but you won’t need to work on everything.)

Cool Zuul

CoolZuul is based on a already extended version done in the labs or programming assignments: Rooms have been refactored to not contain hard-coded assumptions about the setup of the World, Commands have been refactored, and Items been added. Also, a class “GameStatus” has been introduced to store the status of the game during play, which is the current room and the item inventory carried by the sole player. Items can be picked up and dropped in Rooms.

Multiple Players
The CoolZuul game should be extended to allow for multiple players. Each player has their own inventory of items. Players see other players in the same room and can talk to them. There should also be a “shout” command which enables players to communicate with all other players. (Note that you will not be able/know how to implement this until later - don’t worry about that!)
History of Visited Rooms
There should be a history of visited Rooms stored for each player enabling the player to go back more than one step.

Options Choose one of these Options to do CRC cards on.

Option A: Quests
The game should support Quests. Active quests get notified of actions in the game, or by the player, to be able to determine the progress and completion of a Quest. Quests will be advertised on a billboard within the game, and players need to actively start a quest to play and complete it. Players can see a list of started and completed quests.

   ... there is a huge billboard...
   > read billboard
   You read the billboard - it contains a list of quests!
   - teddy: find Teddybear: find the lost Teddybear in the Forest.
   - supper: collect Mushrooms: collect enough Mushrooms for supper.
        Be careful not to use poisonous ones!
   > start supper
   You've started Quest "supper"
    ...
    Congratulations! You successfully made supper.

Option B: Special Items

Interaction with Items there should be special items which allow for interaction, e.g. books that can be read, boxes that can be opened. Items can be contained in other items.

 Some Room Description...
 Items:
 - strange box
 > open box
 There is a key in the box!
 (key is moved to inventory of player.)

 Some Room Description...
 Items:
 - a book
 > read book
      ... quest description or hint follows...

Hidden Items
There should be Items which are not immediately visible. A command “examine” should be introduced to reveal these items. e.g enabling this interaction:

  ....
  There is a strange blob on the wall
  > examine blob
  You examine the blob closer. It is an old chewing gum with a key hidden under it!
  Items:
    - key
  > take key

Option C: Closed Doors and blocked passages
Exits to other Rooms can be blocked by Doors, which may be easy to open or locked with a key. They may also be blocked by something or otherwise hidden. They are similar to items or hidden items, in such that the room description should contain a hint that they are there, and can be interacted with. Some examples:

    There is a door to the north.
    > open door
    You open the door.
    > go north

    There is a door to the south.
    > open door
    You dont have a key.
    > use key on door
    You open the door.
    > go south

    You see a forest. There is a big stone.
    > examine stone
    You examine the stone closer and manage to move it.
    There is a hidden passage down!
    Exits:
    - down
    > go down

Option D: Clothing There should be clothing to wear. Clothing can be found in rooms like other items. After picking up the clothing item it can be worn with the command “wear” and taken off again with “remove”. Only one sort of clothing can be worn, e.g. one pair of trousers, one shirt, one armour, one pair of shoes, one helmet.
```
     ...
     > wear helmet
     You wear your helmet.
     > wear boots
     You are already wearing sandals.
     > remove sandals
     You take off your boots.
     > wear boots
     You are wearing your boots.
     > inventory
     You are wearing your helmet.
     You are wearing your boots.
     Inventory:
       - a key
```
Non-Person-Characters in the game.
Option E: NPCs (for the bored)
There should be Non-Person-Characters in the game.

2. Identify Class and Method Candidates

The first step is to discover some candidate classes and methods.

A simple method to discover candidates for classes, introduced by Abbott (1983), and later popularized by Booch (e.g. Booch 2004, P 136) is the following:

Underline all the nouns (in an English language text) in one color, such as blue
Underline all the verbs in another color, such as red
Underline all the adjectives in a third color, such as green.

The nouns are candidates for classes, the verbs for methods and the adjectives for attributes/fields.

Be aware that this method has later been critized for not beeing a rigourous approach and only being useful for simple problems, and that you get possible candidates for classes and methods - not every noun will be a class name in your application!

3. CRC Cards

Preparation

Get a pack of A6 index cards or simply cut A4 papers twice. Make CRC cards for each of the existing classes as well as of your candidate classes. Only put down the class names for now.

It is really important that you use individual cards! You will need and want to move them, discard them, replace them. See the picture above!

Note: The above requirements are a lot! Only work on one of the marked parts - you may, of course, do more if you want to.

Work through the Scenarios

The examples above how it should be able to interact with CoolZuul constitute scenarios. Work through them and refine your CRC cards based on what you discover. Ask these questions:

How is this done, exactly? What data is going to have to be stored? Where? If you feel the need to create a new class, feel free to do so! If you discover that a class needs to be split in two - make two new cards and rip up the old one. If two need to be merged, do so. Keep a list of things you want to keep track of.

Some of the requirements may need to be clarified by writing down an interaction example first.

Dont’t worry about the Implementation!

Don’t worry if you are unsure how to implement certain things - e.g. the persistence part or differentiating the input from multiple players.

This assignment is about design - you just need to identify that there is something that needs to be taken care of somewhere; without making decisions about the implementation just yet.

Repository for this Lab

https://github.com/htw-imi-info2/lab02-cool-zuul

Lab Report / What to turn in

All info on the lab reports can be found on the Labs page.

Additional requirements for this lab:

Please submit your final CRC cards and a description of the process you went through for creating them.