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Cozmo Song Match
PROGRAMMERS
GUIDE
Brought to you by Cozmo Design Studios
Casey Boyer, Shaon Islam, Sam Schuler, Sefik Mehmedovic, and Dishant Shrestha
1
INDEX
INTRODUCTION ............................................................................................................. 4
Game Objective ........................................................................................................ 4
Links ......................................................................................................................... 4
INITIAL SETUP ............................................................................................................... 5
Prerequisites ............................................................................................................. 5
SDK Example Programs ........................................................................................... 5
Installation................................................................................................................. 5
TROUBLESHOOTING .................................................................................................... 6
Failure to Install Python Package ............................................................................. 6
Cozmo SDK Forums ................................................................................................. 6
INSTALLATION MACOS / OS X .................................................................................... 7
Installation Videos ..................................................................................................... 7
Python Installation .................................................................................................... 7
SDK Installation ........................................................................................................ 7
SDK Upgrade............................................................................................................ 8
Mobile Device Setup ................................................................................................. 8
Troubleshooting ........................................................................................................ 8
INSTALLATION WINDOWS ........................................................................................... 9
Installation Videos ..................................................................................................... 9
Python Installation .................................................................................................... 9
Important................................................................................................................... 9
SDK Installation ........................................................................................................ 9
SDK Upgrade.......................................................................................................... 10
Mobile Device Setup ............................................................................................... 10
Troubleshooting ...................................................................................................... 10
2
LINUX INSTALLATION ................................................................................................ 11
Warning .................................................................................................................. 11
Ubuntu 14.04 .......................................................................................................... 11
Python Installation ............................................................................................ 11
Ubuntu 16.04 .......................................................................................................... 12
Python Installation ............................................................................................ 12
SDK Installation ...................................................................................................... 12
SDK Upgrade.......................................................................................................... 12
Mobile Device Setup ............................................................................................... 13
Troubleshooting ...................................................................................................... 13
ANDROID DEBUG BRIDGE ......................................................................................... 14
Important................................................................................................................. 14
macOS Installation .................................................................................................. 14
Windows Installation ............................................................................................... 15
Linux Installation ..................................................................................................... 16
FINAL INSTALLATION (ALL PLATFORMS) ............................................................... 17
GETTING STARTED WITH THE COZMO SDK ........................................................... 18
Cozmo SDK Forums ............................................................................................... 18
Starting Up the SDK ............................................................................................... 18
Setup ...................................................................................................................... 19
Starting the Game ................................................................................................... 20
NEW FEATURES.......................................................................................................... 21
Multiple Game Modes ............................................................................................. 21
Additional Instruments ............................................................................................ 22
Cube Pagination Menu ........................................................................................... 22
New Songs ............................................................................................................. 23
3
FUTURE EXPANSIONS ............................................................................................... 24
More Instruments .................................................................................................... 24
Multiple Notes per Cube ......................................................................................... 24
Ear Training Mode Expansion................................................................................. 24
Modify Sequence Playback..................................................................................... 25
PYCHARM .................................................................................................................... 26
Finding Usages ....................................................................................................... 26
Note ........................................................................................................................ 27
Enforcing PEP 8 ..................................................................................................... 27
So Much More ........................................................................................................ 28
CODEBASE CONVENTIONS ....................................................................................... 29
Design Patterns ...................................................................................................... 29
Wrapper Objects ..................................................................................................... 29
OBJECT CREATION PATTERNS ................................................................................ 30
Static Factory Methods ........................................................................................... 30
Factories ................................................................................................................. 30
Inheritance .............................................................................................................. 30
Public, Protected, and Private ................................................................................. 31
Type Hinting............................................................................................................ 31
4
INTRODUCTION
Game Objective
Song Match is a game where you try to match the notes of a song by tapping blocks
with Cozmo. There are three separate game modes: Song Match (the main game),
Tutorial Mode, and Ear Training Mode.
Currently, since Cozmo only supports three cubes, songs with only three notes are
used.
Links
The source code for the expanded Song Match game, with the new features added by
Cozmo Design Studios, can be found here
The User guide for the expanded Song Match game can be found here
The source code for the original Song Match game, implemented by the Cozmonauts,
can be found here
5
INITIAL SETUP
To use the Cozmo SDK, the Cozmo mobile app must be installed on your mobile device
and that device must be tethered to a computer via USB cable.
Prerequisites
•
Python 3.5.1 or later
•
Wi-Fi connection
•
An iOS or Android mobile device with the Cozmo app installed, connected to the
computer via USB cable
SDK Example Programs
Anki provides example programs for novice and advanced users to run with the SDK.
Download the SDK example programs here:
•
macOS/Linux SDK Examples
•
Windows SDK Examples
Once downloaded, extract the packaged files to a new directory.
Installation
To install the SDK on your system, see the instructions for your computer’s operating
system.
•
Installation - macOS / OS X
http://cozmosdk.anki.com/docs/install-macos.html
•
Installation – Windows
http://cozmosdk.anki.com/docs/install-windows.html
•
Installation – Linux
http://cozmosdk.anki.com/docs/install-linux.html#install-linux
6
TROUBLESHOOTING
Failure to Install Python Package
If your attempt to install Python packages such as NumPy fails, please upgrade your pip
install as follows:
On macOS and Linux:
pip3 install -U pip
On Windows:
py -3 -m pip install -U pip
Once the pip command is upgraded, retry your Python package installation.
Cozmo SDK Forums
Please visit the Cozmo SDK Forums to ask questions, find solutions and for general
discussion.
7
INSTALLATION
MACOS / OS X
This guide provides instructions on installing the Cozmo SDK for computers running
with a macOS operating system.
Installation Videos
For your convenience, videos are provided showing the installation steps being followed
on a macOS / OS X computer; one using an iOS device, and one using an Android
device. There is also full text-based documentation below these.
https://youtu.be/zNgmUwuHq-M
https://youtu.be/6xWuhOtkfsc
Python Installation
1. Install Homebrew on your system according to the latest instructions. If you
already had brew installed, then update it by opening a Terminal window and
typing in the following:
2. brew update
3. Once Homebrew is installed and updated, type the following into the Terminal
window to install the latest version of Python 3:
4. brew install python3
SDK Installation
To install the SDK, type the following into the Terminal window:
pip3 install --user 'cozmo[camera]'
Note that the [camera] option adds support for processing images from Cozmo’s
camera.
8
INSTALLATION
MACOS / OS X
CONTINUED
SDK Upgrade
To upgrade the SDK from a previous install, enter this command:
pip3 install --user --upgrade cozmo
Mobile Device Setup
•
iOS devices do not require any special setup in order to run the Cozmo SDK on
a macOS system.
•
Android devices require installation of Android Debug Bridge (adb) in order to
run the Cozmo SDK. This is required for the computer to communicate with the
Android mobile device over a USB cable and runs automatically when required.
Troubleshooting
Please see the Troubleshooting section of the Initial Setup page for tips or visit
the Cozmo SDK Forums to ask questions, find solutions, or for general discussion.
9
INSTALLATION
WINDOWS
This guide provides instructions on installing the Cozmo SDK for computers running
with a Windows operating system.
Installation Videos
For your convenience, videos are provided showing the installation steps being followed
on a Windows computer; one using an iOS device, and one using an Android device.
There is also full text-based documentation below these.
https://youtu.be/gtRS3iqzSuA
https://youtu.be/9TJeK_AEFYo
Python Installation
Download the Python 3.5.1 (or later) executable file from Python.org and run it on your
computer.
Important
We recommend that you tick the “Add Python 3.5 to PATH” checkbox on the Setup
screen.
SDK Installation
To install the SDK, type the following into the Command Prompt window:
pip3 install --user cozmo[camera]
Note that the [camera] option adds support for processing images from Cozmo’s
camera.
10
INSTALLATION
WINDOWS
CONTINUED
SDK Upgrade
To upgrade the SDK from a previous install, enter this command:
pip3 install --user --upgrade cozmo
Mobile Device Setup
•
iOS devices require iTunes to ensure that the usbmuxd service is installed on
your computer. Usbmuxd is required for the computer to communicate with the
iOS device over a USB cable. While iTunes needs to be installed, it does not
need to be running.
•
Android devices require installation of Android Debug Bridge (adb) in order to
run the Cozmo SDK. This is required for the computer to communicate with the
Android mobile device over a USB cable and runs automatically when required.
Troubleshooting
Please see the Troubleshooting section of the Initial Setup page for tips or visit
the Cozmo SDK Forums to ask questions, find solutions, or for general discussion.
11
LINUX INSTALLATION
This guide provides instructions on installing the Cozmo SDK for computers running
with an Ubuntu Linux operating system.
Warning
The Cozmo SDK is tested and supported on Ubuntu 14.04 and 16.04. Anki makes no
guarantee the Cozmo SDK will work on other versions of Linux. If you wish to try the
Cozmo SDK on versions of Linux other than Ubuntu 14.04 or 16.04, please ensure the
following dependencies are installed:
•
Python 3.5.1 or later
•
pip for Python 3 (Python package installer)
•
Android command-line tools
(https://developer.android.com/studio/index.html#Other)
•
usbmuxd for iOS / Android Debug Bridge for Android
Ubuntu 14.04
Python Installation
1. Type the following into your Terminal window to install Python 3.5:
sudo add-apt-repository ppa:deadsnakes
sudo apt-get update
sudo apt-get install python3.5 python3.5-tk
2. Then, install and set up virtualenv:
sudo apt-get install python-pip
pip install virtualenv
virtualenv -p python3.5 ~/cozmo-env
3. Last, make sure to activate the virtualenv any time you use cozmo:
source ~/cozmo-env/bin/activate
4. Note: You’ll need to activate the virtualenv before running any python or pip
commands. Learn more about virtualenv here.
12
LINUX INSTALLATION
CONTINUED
Ubuntu 16.04
Python Installation
1. Type the following into your Terminal window to install Python:
sudo apt-get update
sudo apt-get install python3
2. Then install pip by typing in the following into the Terminal window:
sudo apt install python3-pip
3. Last, install Tkinter:
sudo apt-get install python3-pil.imagetk
SDK Installation
To install the SDK, type the following into the Terminal window:
pip install 'cozmo[camera]'
Note that the [camera] option adds support for processing images from Cozmo’s
camera.
SDK Upgrade
To upgrade the SDK from a previous install, enter this command:
pip install --upgrade cozmo (For Ubuntu 14.01)
pip3 install --user --upgrade cozmo (For Ubuntu 16.04)
13
LINUX INSTALLATION
CONTINUED
Mobile Device Setup
•
iOS devices require usbmuxd in order to run the Cozmo SDK. Usbmuxd is
required for the computer to communicate with the iOS device over a USB cable.
•
Android devices require installation of Android Debug Bridge (adb) in order to
run the Cozmo SDK. This is required for the computer to communicate with the
Android mobile device over a USB cable and runs automatically when required.
Troubleshooting
Please see the Troubleshooting section of the Initial Setup page for tips or visit
the Cozmo SDK Forums to ask questions, find solutions, or for general discussion.
14
ANDROID DEBUG
BRIDGE
Important
Android Debug Bridge (adb) is required ONLY for those users pairing an Android mobile
device with Cozmo. Android Debug Bridge (adb) is necessary for the Cozmo SDK to
work with Android mobile devices. Please ensure adb is installed before attempting to
run the Cozmo SDK with a paired Android device.
macOS Installation
1. Type the following into a Terminal window (requires Homebrew to be installed):
brew tap caskroom/cask
brew cask install android-platform-tools
2. Continue to Final Installation (All Platforms) below to complete installation.
15
ANDROID DEBUG
BRIDGE
CONTINUED
Windows Installation
1. In your internet browser, navigate to this link and download file platformtools-latest-windows.zip to your Downloads folder.
2. Open a File Explorer window to your Downloads folder and see that your
downloaded file platform-tools-latest-windows.zip is there.
3. Open a new File Explorer window and create a new folder in
C:\Users\your_name named Android. Then, navigate into your new Android
folder. You should now be inside folder C:\Users\your_name\Android.
4. Move the zip file you downloaded in step 1, platform-tools-latestwindows.zip, to your new Android folder at C:\Users\your_name\Android.
5. Right-click the platform-tools-latest-windows.zip file
in C:\Users\your_name\Android and select Extract All.
6. With File Explorer, navigate to C:\Users\your_name\Android\platformtools-latest-windows\platform-tools and confirm that the adb is there.
You will now add this path to your PATH environment variable in the next step.
7. Add adb to your PATH environment variable.
8. Right-click the Start menu and select System.
9. Select Advanced System Settings -> Advanced -> Environment Variables.
10. Under User Variables, select PATH and click Edit.
11. Under Edit Environment Variables, click New and add the path to the folder
containing adb (e.g. C:\Users\your_name\Android\platform-toolslatest-windows\platform-tools ). Click OK on all dialog boxes to confirm
your change.
12. Confirm that the PATH is correctly pointing to adb.
13. Open new a Command Prompt window. (To find the Command Prompt, you may
use the search box in the lower left-hand corner of your screen.)
14. Type adb and adb instructions should print out.
15. Continue to Final Installation (All Platforms) below to complete installation.
16
ANDROID DEBUG
BRIDGE
CONTINUED
Linux Installation
1. In your internet browser, navigate to this link and download file platformtools-latest-linux.zip. You may need to accept the license before
downloading.
2. Navigate to the zip file download location (e.g., ~/Downloads) and extract the
files. The files will be extracted to folder platform-tools.
3. In your home directory, create folder android-sdk-linux:
cd ~
mkdir android-sdk-linux
4. Move the extracted platform-tools folder to your new android-sdk-linux
folder:
mv Downloads/platform-tools android-sdk-linux
5. Confirm you see adb inside platform-tools:
cd android-sdk-linux/platform-tools
ls adb
6. Add adb to your PATH.
7. Edit your ~/.bashrc file and add this line:
export PATH=${PATH}:~/android-sdk-linux/platform-tools
8. Save .bashrc and then call:
source .bashrc
9. Confirm that adb is in your PATH by calling the following command:
which adb
10. The result of this command should be the path where adb is installed.
11. Continue to Final Installation (All Platforms) below to complete installation.
17
FINAL INSTALLATION
(ALL PLATFORMS)
1. Enable USB Debugging on your phone.
a. On Android devices:
i. Tap seven (7) times on the Build Number listed under Settings ->
About Phone.
ii. Then, under Settings -> Developer Options, enable USB
debugging.
b. On Amazon Kindle Fire:
i. Tap seven (7) times on the Serial Number listed under Settings ->
Device Options.
ii. Then, under Settings -> Device Options -> Developer Options, turn
on Enable ADB.
2. Connect your Android device to your computer via USB. When the Allow USB
Debugging? popup displays, tap OK.
3. At the command line, type this command to confirm that your device shows:
adb devices
At least one device should show in the result, for example:
List of devices attached
88148a08
device
If you are required to accept the connection request on the mobile device itself, a
message will appear saying the device is unauthorized. For example:
List of devices attached
88148a08 unauthorized
18
GETTING STARTED
WITH THE COZMO SDK
To make sure you get the best experience possible out of the SDK, please ensure you
have followed the steps in the Initial Setup.
Cozmo SDK Forums
Please visit our Cozmo SDK Forums where you can:
•
Get assistance with your code
•
Hear about upcoming SDK additions
•
Share your work
•
Join discussion about the SDK
•
Be a part of the Cozmo SDK Community!
Starting Up the SDK
1. Plug the mobile device containing the Cozmo app into your computer.
2. Open the Cozmo app on the phone. Make sure Cozmo is on and connected to
the app via Wi-Fi.
3. Tap on the gear icon at the top right corner to open the Settings menu.
4. Swipe left to show the Cozmo SDK option and tap the Enable SDK button.
5. Make sure the SDK examples are downloaded from the Downloads page.
6. On the computer, open Terminal (macOS/Linux) or Command Prompt (Windows)
and type cd cozmo_sdk_examples, where cozmo_sdk_examples is the
directory you extracted the examples into, and press Enter.
19
GETTING STARTED
WITH THE COZMO SDK
CONTINUED
Setup
1. Setup the Cozmo SDK.
a. Please see Initial Setup under the Cozmo SDK documentation.
2. Clone the repository.
a. $ git clone https://github.com/samuelschuler/CS4500.git
3. Navigate to the repository.
a. $ cd cozmo-song-match
4. Install dependencies.
a. $ pip install -r requirements.txt
5. Download and Install PyCharm (Optional)
20
GETTING STARTED
WITH THE COZMO SDK
CONTINUED
Starting the Game
With Cozmo connected, run the main program. For details on connecting Cozmo,
see Getting Started With the Cozmo SDK.
$ python main.py
We support command line arguments for configuring what song you want to play, and
how many players. Use the help flag -h for help.
$ python main.py -h
usage: main.py [-h] [-s S] [-p N]
Play Song Match with Cozmo.
optional arguments:
-h, --help: show this help message and exit
-s S: The song to play. Hot Cross Buns (hcb), Mary Had A Little
Lamb (mhall), Rain Rain Go Away (rrga), (ir) It’s Raining It’s
Pouring, or (ra) Ring Around the Rosie. Defaults to a random
song.
-p N: The number of players for the game, where N is the number
of players. Defaults to None. If None then selecting the number
of players will be handled in game.
21
NEW FEATURES
Multiple Game Modes
Song Match Mode
With each round, the game gets longer and a little harder. Song Match supports up
to 3 players.
The game starts by playing the first three notes of a song. Each time a note is
played, a corresponding cube flashes. The player must match the notes by tapping
the correct sequence of cubes. If the player gets the sequence correct, then Cozmo
tries to match the correct sequence. If either the player or Cozmo gets three notes
incorrect, then they lose the game.
This makes up one round. Each round the length of the sequence increases, until
you reach the end of the song.
Tutorial Mode
The tutorial mode is a mode where one player will go through an entire song step by
step with Cozmo to understand how the game works. Cozmo will point at the cube
to be tapped. In this mode, the light of this cube will flash white five times and will
stay white until tapped. If the player taps the incorrect cube(s) three times, Cozmo
will show them the correct sequence. It is a collaborative game.
Ear Training Mode
The ear-training mode creates a song with three randomly chosen notes. Then,
song is created by randomly creating a sequence from these three chosen notes.
The sequence of notes, which is the entire song, may be anywhere between 5-10
notes long. Additionally, each note in the song sequence is randomly chosen to be
a whole note, half note, quarter note, or an eighth note. The goal of the game is to
train players to audibly recognize notes.
22
NEW FEATURES
CONTINUED
Additional Instruments
The original Song Match game only supported one instrument, Piano. We implemented
an instrument class to support an unlimited number of instruments. Currently, the
Song Match game has the following instruments: Piano, Clarinet, and Flute. Now, an
instrument is randomly selected when a song is played, rather than defaulting to Piano.
To add more instruments, create a new package (named according to your instrument)
under the sound_effects package, and add the instrument .wav files to this package.
Then, in the instrument class under the song_match.song package, declare your
instrument names as strings, and add them to the instrument_dictionary member of
the class.
Warning: when adding new instruments, make sure that the added instrument(s)
have the notes required to play any of the predefined songs. For example, if an
instrument is added that does not have the note ‘D4’, then the instrument cannot play
the song Ring Around the Rosie, since this is a note in the song. As a result, we added
a unit testing for each new instrument added, which you can find in the
test_note_instrument class under the test package. This should clarify the
differences between the instruments, and which instruments support what notes.
Cube Pagination Menu
Previously, the only time Cozmo asked for the user input in the form of cube taps was
when asking how many players and during the gameplay. Now, we have modified the
option_prompter class under the song_match package such that it:
•
accepts a list of three str elements representing options that Cozmo will prompt
the user with
• accepts a list of three str elements representing the Cozmo’s response based
on the option selected
• the return value will represent the cube tapped, and is used to obtain the option
selected by the user
In doing so, we were able to implement a pagination for selecting the game mode and
for whether the user wishes to continue playing after a game is over.
23
NEW FEATURES
CONTINUED
New Songs
We added two more songs, Ring Around the Rosie and It’s Raining It’s Pouring.
Now, the Song Match game has 5 total songs to choose from:
•
•
•
•
•
Mary Had a Little Lamb
Hot Cross Buns
Rain Rain Go Away
Ring Around the Rosie
It’s Raining It’s Pouring
24
FUTURE EXPANSIONS
More Instruments
Currently, only one instrument plays a given song. While any of the songs may play with
any of the three instruments, it would be interesting for one song to play with multiple
instruments. This may involve assigning a unique instrument to each of the cubes,
assigning an instrument for specific notes in the song sequence, etc. With this
implementation, the player(s) would also have to pay closer attention to the instruments
in addition to the notes being played.
Multiple Notes per Cube
Cozmo will only recognize the first distinct three cubes placed in front of him. This
means he will not recognize additional cubes. So, adding more cubes will not allow
songs to be created with more than three notes. Thus, it would open a wider range of
songs to implement if each cube could be associated with multiple notes rather than
one note per cube. This would allow you to create songs with 4, 5…,n notes. Currently,
the three note limitation is a severe hinderance, as not many recognizable three note
nursery rhymes exist. Naturally, this leads to implementing difficulty modes such as
easy, medium, and difficult, depending on the note complexity of a song.
Ear Training Mode Expansion
The Ear Training Mode is quite similar to the Song Match Mode, with the main
difference being that the song is randomly created. To better train the player(s) to
recognize different note pitches, this mode could be restructured to have the user guess
certain pitches played back in a sequence. Additionally, this mode could be modified to
have Cozmo prompt the user to play a specific note in the sequence, so that the user
must focus more on the sound of the notes rather than the order they are played in.
25
FUTURE EXPANSIONS
CONTINUED
Modify Sequence Playback
In both the Song Match Mode and Ear Training Mode, the game does not end until
either Cozmo or the player(s) repeat the sequence incorrectly three times; this means
that if the player(s) and Cozmo repeat the sequence correctly for the entire song, the
game will not end until the entire song is played. Although the maximum number of
notes in a song sequence is not more than 20, this can take a long time to play through
– and is difficult for age groups above the 4-6 age range. So, the sequence playback
should be modified in such a way that the user can more easily repeat the song
sequence.
26
PYCHARM
The following aims to explain why we recommend using PyCharm to develop Song
Match.
If you haven’t already, download and install PyCharm Community Edition here:
https://www.jetbrains.com/pycharm/download/
Finding Usages
The first reason we recommend you use PyCharm is the ability to find usages. Often
when developing you need to find all the places where a function is called. PyCharm
makes this easy.
For example, here’s a function that checks for whether the game is over in
song_match.py:
If you hover over the name of the function while holding Ctrl, and click the name of the
function you can find usages.
PyCharm also has other keyboard shortcuts and ways to find usages that are helpful to
learn.
27
PYCHARM
CONTINUED
The tooltip window shows the function is called in two places:
•
Line 98 in song_match.py
•
and line 117 in song_match.py
You can select either usage and PyCharm will automatically navigate there for you.
Note
Finding usages works for functions, methods, variables, and anything else you could
care about.
Enforcing PEP 8
PyCharm also helps developers follow Python’s official style guide PEP 8.
For example, PEP 8 states variables should use snake case instead of camel case.
PyCharm underlines the camelcase variable with a yellow squiggly line and suggests
renaming it from numPlayers to num_players.
28
PYCHARM
CONTINUED
So Much More
PyCharm offers many other great features that are outside the scope of this document
like:
•
Integration with requirement.txt files
•
Powerful refactoring abilities
•
Creating and Optimizing imports
•
Reformatting source code
•
and so much more.
29
CODEBASE
CONVENTIONS
The following aims to explain some of the common conventions found within the Song
Match codebase.
Design Patterns
The Song Match codebase is almost entirely object oriented. There are many design
patterns relating to object-oriented programming (OOP) found throughout the codebase.
Wrapper Objects
The first design pattern you’ll see are our use of wrapper objects. A “wrapper object” is
an object that takes an already instantiated object in its constructor and extends its
functionality through custom methods.
More formally this is known as the Decorator Pattern because your decorating an object
by wrapping it and adding behavior.
Common objects from the Cozmo SDK, like the objects representing Cozmo and the
cubes, have a corresponding wrapper object in the Song Match codebase:
•
SongRobot wraps Robot
•
NoteCube wraps LightCube
•
NoteCubes wrap a list of 3 LightCube instances
Many methods and properties of the wrapper objects match the corresponding wrapped
object. For example, both NoteCube and LightCube have a set_lights method.
The set_lights() method in NoteCube simply calls set_lights() on the internal
LightCube object.
# note_cube.py
def set_lights(self, light: Light):
self._cube.set_lights(light)
30
OBJECT CREATION
PATTERNS
Static Factory Methods
A static factory method is a static method used for creating an object.
There are two static factory methods in the codebase. Both are methods named of, a
concise naming convention for static factory methods popularized by EnumSet in Java.
See How to name factory like methods? for more details.
•
NoteCube – of()
•
NoteCubes – of()
Factories
A factory is an object for creating other objects.
In our codebase there is one factory, EffectFactory.
EffectFactory creates our various game effect subclasses:
•
CorrectSequenceEffect - Played when a player matches the correct notes.
•
RoundTransitionEffect - Played when transitioning between game rounds.
•
WrongNoteEffect - Played when a player fails to match the correct notes.
Inheritance
We favor composition over inheritance and avoid complex class hierarchies.
No class extends an instantiable class, but there are two abstract base classes:
•
Effect - Abstract base class for various game effects
•
Song - Abstract base class for various songs
31
OBJECT CREATION
PATTERNS
CONTINUED
Public, Protected, and Private
Python lacks access modifiers like private and protected found in languages like
Java and C#.
We follow the convention of preceding private methods and attributes with two
underscores. For example:
def __some_private_method():
pass
protected methods and attributes are preceded with a single underscore.
def _some_protected_method():
pass
If you see anything that begins with an underscore, then it means don’t use it outside of
that class or module.
In general, all public members in Song Match have docstring comments, while
private and protected members do not.
Type Hinting
In general, all functions and methods are type hinted. Below we see a function that adds
two int values together, and returns an int.
def add_two_numbers(a: int, b: int) -> int:
return a + b
See support for type hints for more details.
Source Exif Data:
File Type : PDF File Type Extension : pdf MIME Type : application/pdf PDF Version : 1.7 Linearized : No Page Count : 32 Language : en-US Tagged PDF : Yes XMP Toolkit : 3.1-701 Producer : Microsoft® Word for Office 365 Title : Programmers Guide Creator : Samuel Creator Tool : Microsoft® Word for Office 365 Create Date : 2018:12:12 00:16:09-06:00 Modify Date : 2018:12:12 00:16:09-06:00 Document ID : uuid:A19DC0A3-887F-4249-A75A-A110B0FFBE3B Instance ID : uuid:A19DC0A3-887F-4249-A75A-A110B0FFBE3B Author : SamuelEXIF Metadata provided by EXIF.tools