CSCI3180 – Principles of Programming Languages  Assignment 3

CSCI3180 – Principles of Programming Languages 
Assignment 3 — Perl and Dynamic Scoping

1 Introduction
The purpose of this assignment is to offer you the first experience with Perl, which supports both
dynamic and static scoping. Our main focus is on dynamic scoping.
The assignment consists of three parts. First, you are required to implement a popular card game
called “Golden Hook Fishing” in Perl. Second, you need to implement a simplified Monopoly game
in Perl with dynamic scoping. Third, you are required to re-implement the simplified Monopoly
game using Python with static scoping. The detailed Object-Oriented (OO) design for both the Perl
and Python implementations are given. In the process, you will experience both the programming
flexibility and readability (good or bad) with dynamic scoping. Your implementation should be
able to run on our VM environment with Perl v5.18.2 and Python 3.4.0. Besides, you are required
to add “use warnings;” and “use strict;” at the start of your program. Good coding styles are
expected.
IMPORTANT: All your codes will be graded on the VM. You are welcome to write and test
your codes in your own computing environments, but please test them on the given VM before
your submission (run your Python code with python3 command instead of python on the VM).

2 Task 1: Golden Hook Fishing
In this task, you need to implement the “Golden Hook Fishing” game. You should strictly follow
the specified OO design and game rules for this task. For the OO design, you have to follow the
prototypes of the given classes exactly, but can choose to add new member variables and methods.
2.1 Description
There are 52 cards excluding “Joker” in a deck. At the beginning of each game, the deck is shuffled
and distributed to N players evenly. In our game, we assume 52 is to be divisible by the player’s
number N. Besides, players cannot see the cards assigned to them. In other words, a deck of 52
cards is divided into N decks of 52/N cards to each player and none of them can see the cards.
Then players take turns to play cards. In each player’s turn, he/she takes a card from the top of
the his/her deck and adds it to the tail of the desktop card stack. If there is another same-character
card in the stack, the players can take the cards between these two cards (include these two cards)
and put them at the bottom of his/her deck. A special situation is that if the player takes
a “J” from the top of his/her deck, he/she can take all the cards on the desktop card
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stack to himself/herself. To make it possible to end the game in limited rounds, this situation
is established if and only if the desktop card stack is not empty before a “J” is taken from the
deck. In other words, if the “J” is the only card in the desktop card stack, then the ”J” will be
left in the desktop card stack as a regular card and the player will get nothing. A player is out
when the player has no cards in his/her deck. The game will end when only one player remains.
The last remaining player is the winner.
2.2 Perl Classes
Please follow the classes Deck, Player, Game defined below in your Perl implementation. You
are free to add other variables, methods or classes. We would start the program by running:
GoldenHookFishing sample1(2).pl
1. Class Deck (You are not allowed to modify this class)
An abstraction of a deck of cards. You have to implement it with the following components:
• Instance Variables
cards
– This variable is the reference to a one-dimensional array recording initial cards in
the deck. Each card is represented using the character in the face of this card. Suit
information can be ignored since it will not affect the value of a card.
• Instance Method(s)
new
– Instantiate a Deck object with a deck of 52 cards without shuffling, and return this
object.
shuffle
– Shuffle all cards in the deck. Please strictly follow our design to call this function.
AveDealCards(num)
– Return an array of num reference of divided cards.
2. Class Player
A super class representing a participant in the game. You have to implement it with the
following components:
• Instance Variable(s)
name
– This is a variable recording the name of the participant.
cards
– This variable is the reference to a one-dimensional array recording cards in the
player’s deck.
• Instance Method(s)
new(name)
– Instantiate a Player object with its name, and return this object.
getCards(card)
– Put the taken cards to the bottom of his/her deck.
dealCards
– Take a card from the top of his/her deck and deal it to the game.
numCards
– Return the number of player’s cards.
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3. Class Game
This class represents the process of the cards game. You have to implement it with the
following components:
• Instance Variable(s)
deck
– This is a Deck object.
players
– This variable is the reference to a one-dimensional array recording all players in the
game. This array naturally encodes the order of all players.
cards
– This variable is the reference to a one-dimensional array recording the desktop card
stack during the game.
• Instance Method(s)
new
– Instantiate a variable deck with a Deck object and an array to record players.
setPlayers(players name)
– “players name” is a reference to a one-dimensional array recording the name of the
players. The players variable will be instantiated by the players name.
getReturn
– Calculate how many will be returned to the player from the current desktop card
stack. The operation follows the rule in description.
showCards
– Show the cards on the cards stack.
startGame
– Start a new game. First, deck will be shuffled and each participant will get a deck
of cards evenly. And then players will deal cards and get cards by turn. In each
player’s turn, he/she firstly deals a card and then get some or no return according
to the rule. Finally, the winner will be shown. You are required to output very
important information in this function and more details can be found in the output
specifications.
2.3 Output Specification
You need to output some required information of the game. Please refer to the output sample for
more details.
2.4 Grading Criteria
The package “MannerDeckStudent.pm” inherits the “Deck.pm” package and implements the shuffle
method, which uses a certain algorithm to shuffle the deck. Besides, we also provide students
with two input samples, “GoldenHookFishing sample1.pl” and “GoldenHookFishing sample2.pl”,
as well as their corresponding output, “output sample1.txt” and “output sample1.txt”. Students
can use them to test the correctness of their programs.
For scoring, we will modify the algorithm in “MannerDeckStudent.pm” and compare the output
from students’ program and standard output. We will use several test samples and only
absolutely same outputs can get marks.
To be fair, the codes of “Deck.pm” and “MannerDeckStudent.pm” will be given to students. You
only need to implement the “Player.pl” and “Game.pl” packages.
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3 Task 2: Monopoly
In this task, you need to implement a simplified Monopoly game in Perl. Note that dynamic
scoping is beneficial and required here, and you need to explain why your implementation using
dynamic scoping (specifically, with the “local” keyword in Perl) is more convenient.
With dynamic scoping, you can 1) implicitly affect the behaviour of functions by function calling
sequences without passing extra parameters, and 2) temporarily mask out some existing variables.
Full marks on this task demands you to show both of these two properties with your code and
explanations.
You should strictly follow our OO design in you implementation. You have to follow the prototypes
of the classes given in the template exactly, and are not allowed to modify the existing codes in
the template. You can choose to add new member variables and functions if necessary.
3.1 Background
Monopoly is a board game currently published by Hasbro. In the game, players roll two six-sided
dice to move around the game board, buying and trading properties, and developing land with
houses and hotels. Players collect rent (toll) from their opponents, with the goal of driving them
into bankruptcy. Money can also be gained or lost through Chance and Community Chest cards,
and tax squares; players can end up in jail, from which they cannot move until they have met one
of several conditions. The game has numerous house rules, hundreds of different editions, as well as
many spin-offs and related media. Monopoly has become a part of international popular culture,
having been licensed locally in more than 103 countries and printed in more than 37 languages.
3.2 Task Description
You are required to implement a simplified Monopoly game that only involves two players: Player
A and Player B. The game board is organized as a 10 × 10 square (36 slots in total) as shown in
Figure 1, and has three kinds of slots: Bank, Land, and Jail. When players step on different slots,
they will do different actions.
Both players start from the “Bank” with $100,000 and move clock-wisely. This game is turnedbased, meaning the two players make moves alternately. Player A moves first. In each round, the
players roll a six-sided dice in turn to decide how many steps to take. A Fixed cost of $200 will
be charged per round, even if the player is in Jail. Notice that if the player does not have enough
money to pay the fixed cost, the amount he/she has to pay is the amount he/she has. The player
can pay an extra $500 to roll two dice and add up the numbers. When one of the players runs out
of money, the game ends with the other player as the winner.
Figure 1: The game board
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We explain the types of state and relevant rules as follows:
• Bank: A player who steps on the “Bank” collects $2,000 from the bank.
• Jail: A player who steps on a “Jail” stops for two rounds by default, but the player can stop
for only one round if he/she pays $1,000.
• Land:
1. If a player steps on an unowned piece of land, the player can buy the land with $1000,
but can also choose to decline this purchase. The development level of the land is
initially 0.
2. If a player steps on the land owned by him/herself, the player can choose to upgrade
the development level of the land or not. There are four levels of land: 0, 1, 2 and 3.
The land must be upgraded gradually, i.e., the player can only upgrade the land to level
i when it is level i − 1.
3. If a player steps on the land owned by the other player, the player must pay the owner
a given toll; the amount depends on the development level of the land.
4. More explanation of “Land” is shown in Figures 2-4.
• Tax: Whenever a player receives income (e.g., receiving money when steps on Bank or receiving toll from the other player), tax will be charged. The tax rate varies according to different
types of income as shown in Table 1.
• Handling fee: Whenever a player needs to pay (e.g., paying for toll or reducing prison rounds
in Jail), handling fee will be charged. The handling fee rate varies according to different
types of payments as show in Table 1.
Action amount tax rate handling fee rate
Buy land 1000 / 0.1
Upgrade to level 1 1000 / 0.1
Upgrade to level 2 2000 / 0.1
Upgrade to level 3 5000 / 0.1
Pay toll of level 0 land 500 / 0
Pay toll of level 1 land 1000 / 0
Pay toll of level 2 land 1500 / 0
Pay toll of level 3 land 3000 / 0
Receive toll of level 0 land 500 0.1 /
Receive toll of level 1 land 1000 0.15 /
Receive toll of level 2 land 1500 0.2 /
Receive toll of level 3 land 3000 0.25 /
Pay to throw two dice 500 / 0.05
Pay to reduce prison rounds 1000 / 0.1
Receive money from Bank 2000 0 /
Fixed cost for every round 200 / 0
Table 1: The cost/income of different actions in the game.
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Figure 2: If the player steps on an unowned piece of land
Figure 3: If the player steps on the player’s own land
Figure 4: If the player steps on the other player’s land
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Hint Implement non-default cases via dynamic scoping. The basic logic of the game is presented
in “monoply.pl”, “Bank.pm”, “Jail.pm” and “Land.pm” and “Player.pm”, the templates of which
have been provided to you. Please check the files for more details.
3.3 Perl Implementation Template
Please follow the classes Bank, Jail, Land, and Player defined below in your Perl implementation.
You are free to add other variables, methods or classes, but cannot modify/delete ours. Please
stick to our naming conventions. We would start the program by running: perl monopoly.pl. The
template for the Python implementation is also provided in “monoply.py” and follows exactly the
same structure of the Perl implementation.
1. Class Player (You are not allowed to modify this class)
• Instance Variables
name
– Name of the player, which will be displayed on the game board.
money
– Total amount of money the player has, which is initially $100,000.
position
– The position of the player. The value of position is 0 when the player is at the
Bank slot of the game board. The value increments clock-wisely and is reset to 0
at Bank slot.
num rounds in jail
– The number of rounds remained in which the player cannot move.
• Instance Method(s)
new
– Initializer of the Player instance.
move
– If the player is not in jail (i.e., num rounds in jail = 0), move the position of the
player according to the number of dice. Otherwise, decrease the num rounds in jail
by 1.
payDue
– Update the player’s money according to values stored in income, due, tax rate,
handling fee rate. See the code template for concrete formula.
putToJail
– This method will be called when the player steps on a Jail slot. The instance variable
num rounds in jail is updated according to the value stored in prison rounds.
printAsset
– Display the asset of the player.
2. Class Bank (in “Bank.pm”)
• Instance Method(s)
new
– Initializer of the Bank instance. You can add additional instance variables here if
needed.
print
7
– This method determines how Bank is displayed on the game board. Please do not
modify this method.
stepOn
– This method is called when a player steps on the corresponding Bank slot. You
are required to implement the rule of Bank according to Section 3.2. Your program
should output “You received $2000 from the Bank!” when a player receives money
from the Bank.
3. Class Jail (in “Jail.pm”)
• Instance Method(s)
new
– Initializer of the Jail instance. You can add additional instance variables here if
needed.
print
– This method determines how Jail is displayed on the game board. Please do not
modify this method.
stepOn
– This method is called when a player steps on the corresponding Jail slot. You are
required to implement the rule of Jail according to Section 3.2. When a player steps
on it, your program should ask for user’s input by printing “Pay $1000 to reduce
the prison round to 1? [y/n]” and call putToJail method in Player class according
to the player’s answer. If the player does not have enough money, the program will
output a warning message “You do not have enough money to reduce the prison
round!”.
4. Class Land (in “Land.pm”)
• Instance Method(s)
new
– Initializer of the Land instance. You can add additional instance variables here if
needed.
print
– This method determines how Land is displayed on the game board. Please do not
modify this method.
buyLand
– This method is called when a player wants to buy land. If the player does not
have enough money, the program will output a warning message “You do not have
enough money to buy the land!”, and the player cannot buy the land. You are
required to implement the rule of buying land according to Section here
upgradeLand
– This method is called when a player wants to upgrade the land. If the player does
not have enough money, the program will output a warning message “You do not
have enough money to upgrade the land!”, and the player cannot upgrade the land.
You are required to implement the rule of upgrading land according to Section here
chargeToll
– This method is called when a player steps on a land owned by the other player and
has to pay a toll. You are required to implement the rule of charging toll according
to Section here. Notice that if the player does not have enough money to pay the
toll, the amount he/she has to pay is the amount he/she has.
stepOn
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– This method is called when a player steps on the corresponding Land slot. If the
land is unowned, ask whether the player wants to buy the land by printing “Pay
$1000 to buy the land? [y/n]” and take actions according to the players answer. If
the land is owned by the player, ask whether the player wants to upgrade the land
by printing “Pay $[upgrade fee] to upgrade the land? [y/n]” (replace [upgrade fee]
with the corresponding value) and take actions according to the player’s answer.
If the land is owned by the other player, your program needs to output “You
need to pay player [owner name] $[amount]” (replace [owner name] and [amount]
by corresponding values) and charges the toll.
5. Main file, ”monoply.pl”
• printCellPrefix and printGameBoard
Utilities to print the game board and show the position of players on game board. Do
not modify these two functions.
• throwDice
Return the number of steps the player can move according to the dice. You are not
allowed to modify this function.
• terminationCheck
Check whether game has ended according to the rule. Return 1 if the game has not
ended. Otherwise, return 0.
• main
The entry of the game. Player A moves first. Each round starts by printing the game
board and the players’ money. A message “Player [current player]’s turn.” (replace
[current player] with the corresponding value) is also printed to indicate who is moving
in this round. Your program will ask the player “Pay $500 to throw two dice? [y/n]”
and throw the dice accordingly. If the player does not have enough money, the program
will output a warning message “You do not have enough money to throw two dice!”, and
the player cannot throw two dice. The points of the dice is shown by printing “Points
of dice: [points]” (replace [points] by the corresponding value). Afterwards, the player’s
position is updated accordingly and the new game board is printed. According to where
the player steps on, different actions will be activated according to the rule. A typical
round is shown in Figure 5. After each round, your program should check whether the
game has ended. When the game is ended, print “Game over! winner: [winner name].”
(replace [winner name] with corresponding value). Otherwise, continue to the next
round.
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Figure 5: A typical round
3.4 Input/Output Specification
• Input
The input is simply “y” or “n” representing the players decision. Notice that if the player
enters an invalid answer, i.e., neither “y” nor “n”, your program should ask the player again
until he/she enters a valid answer.
• Output
The codes for printing the game board are given in the skeleton. Do not change them.
The name printed in each slot of the game board represents the type of the slot. The name
of Bank and Jail is simply “Bank” and “Jail”. But notice that we use “Land” to represent an
unowned land and “A:Lv0” to represent Player A owns the land of level 0. Similar notations
are used for Player B and other levels of the land.
The positions of players are shown by prefixing the slot name with the players’ name. For
example, in Figure 5 at the beginning, both Player A and Player B are at the Bank slot, and
later, Player A is moved to postion 7 which is a Land slot.
For other outputs, you should strictly follow the format specified in Section 3.3 (The bluecolored texts).
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3.5 Grading Criteria
Your program should run by calling “perl monopoly.pl” and will be tested this way. You will also
be evaluated on your implementation of the given classes (with dynamic scoping when necessary)
and programming style.
3.6 Implementing Monopoly via Python
In this task, you are asked to implement the Monopoly game using Python with exactly the same
class design. You should adopt and adapt to the class design and skeleton code in Section 3 for
this task. Also, the input/output specifications and grading criteria are the same as those in the
previous task. All your implementations are required to be written into a single Python file named
as “monopoly.py”. Note that Python does not support dynamic scoping.
4 Report
You should give a simple report to answer the following questions within two A4 pages:
1. Provide example code and necessary elaborations for demonstrating the advantages of Dynamic Scoping in using Perl to implement the simplified Monopoly game as compared to the
corresponding codes in Python.
2. Discuss the keyword local in Perl (e.g. its origin, its role in Perl, and real practical applications
of it) and giving your own opinions.
5 Submission Guidelines
Please read the guidelines CAREFULLY. If you fail to meet the deadline because of submission
problem on your side, marks will still be deducted. The late submission policy is as follows:
- 1 day late: -20 marks
- 2 days late: -40 marks
- 3 days late: -100 marks
So please start your work early!
1. In the following, SUPPOSE
your name is Chan Tai Man,
your student ID is 1155234567,
your username is tmchan, and
your email address is tmchan@cse.cuhk.edu.hk.
2. In your source files, insert the following header. REMEMBER to insert the header according
to the comment rule of Perl and Python.
/∗
∗ CSCI3180 Principles of Programming Languages
∗
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∗ --- Declaration ---
∗
∗ I declare that the assignment here submitted is original except for source
∗ material explicitly acknowledged. I also acknowledge that I am aware of
∗ University policy and regulations on honesty in academic work, and of the
∗ disciplinary guidelines and procedures applicable to breaches of such policy
∗ and regulations, as contained in the website
∗ http://www.cuhk.edu.hk/policy/academichonesty/
∗
∗ Assignment 3
∗ Name : Chan Tai Man
∗ Student ID : 1155234567
∗ Email Addr : tmchan@cse.cuhk.edu.hk
∗/
The sample file header is available at
http://course.cse.cuhk.edu.hk/~csci3180/resource/header.txt
3. The report should be submitted to VeriGuide, which will generate a submission receipt. The
report and receipt should be submitted together with your Perl and Python codes in the
same ZIP archive.
4. For task 1, the Perl source should have the filename “Deck.pm”, “Player.pm”, “Game.pm”
and “MannerDeckStudent.pm”. For task 2, the Perl source should have the filename “Land.pm”,
“Bank.pm”, “Jail.pm”, “Player.pm” and “monopoly.pl”. The Python source should have the
filename “monopoly.py”. The report should have the filename “report.pdf”. The VeriGuide
receipt of report should have the filename “receipt.pdf”. All file naming should be followed
strictly and without the quotes.
5. Tar your source files to username.tar. Don’t change the directory structure of the given
code skeleton.
tar cvf tmchan.tar task1 task2 report.pdf receipt.pdf
6. Gzip the tarred file to username.tar.gz by
gzip tmchan.tar
7. Uuencode the gzipped file and send it to the course account with the email title “HW3
studentID yourName” by
uuencode tmchan.tar.gz tmchan.tar.gz \
| mailx -s "HW3 1155234567 Chan Tai Man" csci3180@cse.cuhk.edu.hk
8. Please submit your assignment using your Unix accounts.
9. An acknowledgement email will be sent to you if your assignment is received. DO NOT
delete or modify the acknowledgement email. You should contact your TAs for help if you do
not receive the acknowledgement email within 5 minutes after your submission. DO NOT
re-submit just because you do not receive the acknowledgement email.
10. You can check your submission status at
http://course.cse.cuhk.edu.hk/~csci3180/submit/hw3.html.
11. You can re-submit your assignment, but we will only grade the latest submission.
12. Enjoy your work :>
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