Perl

Homework 4

This assignment involves creating both a general purpose "traditional" module as well as an object-oriented (ie, class) module in Perl

Create a class to model a video membership club account, called Rcsid::VideoClub (where Rcsid is your RCS Id, capitalized). Each account in the club consists of:

• An account holder's name
• An account balance due
• A purchase committment total (ie, must buy 4 more movies to satisfy your requirements)
• A list of previously purchased titles, along with the dates they were ordered.
• An account status - either "active", "fullfilled", or "closed".

Additionally, the club itself has two properties, independent of any individual account:

• Membership list
• A Featured Title for each month of the year (the movie or cd that will be sent to you automatically if you don't send back the reply card)

Class Methods

Methods available to the entire club are:

new_account

Takes the name of a new account holder and a membership requirement, and returns a new club account. Also increases the total membership of the club.

members

In scalar context, returns the number of current members of the club. In list context, returns the names of all current members of the club.

get_account

Takes the name of a member, and returns that member's account object. This method should croak if no such account holder exists.

get_title

Takes a month (from 1 - 12), and returns the featured title for that month.

set_title

Takes a month (from 1 - 12), and a title name, and set's that month's feature to that title

Object Methods

Account objects have their own set of available methods:

get_name

Returns the name of the account holder

get_balance

Returns the current balance due

purchase

Takes a title and an amount. Adds the title to the account's purchase history (at the current date/time stamp), and increase's the account's balance due by the purchase amount. Also reduces the account's membership requirement. If this purchase reduces the requirement to 0, the status should be set from "active" to "fullfilled". This method should croak if the account's status is "closed"

make_payment

Takes an amount, and reduces the account's balance due by that amount.

cancel

Marks the account as closed, and removes it from the club's membership list. However, if the account requirements have not yet been fullfilled, or if the account still has a balance due, this method should croak and not update the account status or membership list.

get_status

Returns the current status of the account, which will be either "active", "fullfilled", or "closed"

show_history

prints to standard output (or whatever the currently selected filehandle is) a formatted list showing the title purchased, the date/time purchased, and the requirements left after purchasing that movie.

Traditional Module

To assist you with the final object method, you will write a generic traditional module, called Rcsid::FormatList. This module does not define any classes or objects or methods. It has only one purpose - to create a general use subroutine named "format_list". This subroutine takes a list of headings, followed by an array of arrays. It returns a single string consisting of the array's alues in a properly formatted list. By "properly formatted", we mean that the list consists of columns. Each column is headed by the header passed in, and there is at least one blank space between each value in each row. The starting position of the columns are consistent across rows. This means you will have to scan the entire list to determine the column widths before building your list. You will almost assuredly want to use the sprintf function for this task. You may read more about it in perldoc -f sprintf.

For example, if I were to call your subroutine like so:

my @list = ( ["Paul", 29], ["Joshua", 8], ["Mary-Beth-Sue-Ann", 19], ["Amy", 100] );
my $formatted_list = format_list("Name", "Age", \@list);

Then $formatted_list would contain:

Name              Age
---------------------
Paul              29 
Joshua            8  
Mary-Beth-Sue-Ann 19 
Amy               100

Remember, FormatList doesn't know anything about VideoClub or its objects. It is a generic module that defines a subroutine that VideoClub::show_history happens to find useful.

Module creation and Documentation & Testing

You should use the h2xs procedures we went over in class on 3/26 to create both VideoClub and FormatList. When you submit, you will submit the two tarballs generated by the make dist command. Don't forget that you will have to get FormatList working and installed in order for VideoClub to compile correctly. To create your two modules, run these commands:
h2xs -AX -n Rcsid::FormatList
h2xs -AX -n Rcsid::VideoClub

You must write POD documentation for both modules. Each document should include a description of the module's purpose, a quick synopsis showing how it's used, a description of each mehod/subroutine, and your name as the copyright holder.

You must also create a test file for each module. I will be posting an overall test file that you can use to test your complete assignment. You should feel free to "borrow" any or all of the tests in this file for your own purposes.

Error Messages

My testing file will be checking for specific errors and associated error messages. Please make sure you make your croak messages match the following:

• get_account passed non-existent account-holder: "No such account holder '<name>'"
• purchase on a closed account: "Closed accounts cannot make purchases
• cancel with balance due: "Account cannot be closed until remaining balance (<balance>) is paid in full"
• cancel before fullfilled: "Account cannot be closed until <requirement> more video(s) is/are purchased"
• format_list with unequal header/row values: "All data rows must have <num headers> values"

Grading Criteria

Penalties

Late and Compilation Penalties remain the same from the first three HWs, -20 points and -50%, respectively..

Error Checking

All methods should be checked for valid input. Any time a method is called without valid input, or on an invalid object, that method should croak with an appropriate error message.

Code Style

Your code should be easily readable to a human being. Most imporant are consistent indentation, explanatory comments, and meaningful variable names. Please see also perldoc perlstyle for a guide to well-styled Perl code.

Output Style

There is no output style criterion for this assignment. The only output your code should directly generate is from the show_history method, and that method has its own criterion.

Submission Instructions

To submit, run make dist on each of your modules to create the two tarballs. On solaris.remote.cs.rpi.edu, run the submit program ~lallip/public/submit.pl and follow the prompts. You should submit only the two tarballs, which will themselves contain your modules' code, documentation, and test files.

Your submission is due at 11:59:59pm EDT Tuesday, April 8, 2008. It will be accepted up to 3:59:59pm Wednesday April 9 at a deduction of 20 points.