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A dictionary for the shopping-with-stock construal


randomIndex A seed for random number selection that can be used to ensure repeatability
price[1-6] The prices of the six items for sale
width* (in comments) The diameters of the 8 coins - width20 is the width of a 20p piece etc
ix[1-8] The indices of the eight coins in the purse in the list of all coins [1,2,5,10,20,50,100,200]
coinsselected An array of 8 boolean values to record which of the coins in the purse have been selected
itemsselected An array of 6 integer values to record how many instances of each of the items have been selected
imagelocation The web address at which the images being retrieved are stored
scaleWidth The scaling factor that is used in specifying the screen layout

Observables defined by dependency

item[1-6] The six items that are for sale, each recorded as a pair comprising a name and price
forsale The complete list of items that are for sale, recorded as [item1, item2, .... , item6]
items The list comprising the six items that are for sale, each recorded as a pair comprising a name and price
basket The list of names of items that have been selected for purchase
bill The total cost of the items that have been selected for purchase
coinlist The list of coins, in which each denomination is recorded as an integer number of pence
purse The coins that the customer has available to spend
spendingmoney The total amount of money that the customer has to spend
haveenoughmoney Whether or not the cost of the currently selected items exceeds the total amount of money the customer has to spend
shortfall How far the cost of the currently selected items exceeds the total amount of money the customer has to spend or zero if the customer has enough money
tendered The amount of money the customer is offering for the items selected
change The amount of change the customer would be entitled to, or zero if the customer hasn't offered enough money
coin[1-8]pic The images used to depict the eight denominations of coin that can appear on the display
item[1-6]pic The images used to depict each of the six items selected (where appropriate) on the display
item[1-6]pic0 The images used to depict each of the six items for sale on the display
coin[1-8]text The text used to display the denominations of the coins belonging to the customer
item[1-6]numtext The text used to display the number of instances of each item selected by the customer
item[1-6]text The text used to display the price of each item for sale
 
PurseContentText The text used to designate the content of the purse on the display
CoinsInHandText The text used to designate the coins tendered on the display
BasketContentText The text used to designate the content of the basket on the display
ItemsForSaleText The text used to designate the items for sale on the display
 
picture The built-in observable used to specify the list of drawable components on the display
optpic[1-6] The optional drawable components used to display the items that have been selected by the customer

The following user-defined functions are used to express dependency relationships:

listitems Making a list of the selected items
costitems Calculating the cost of the selected items
moneyinhand Calculating the amount of money tendered
coindisplay Determining which image to display given an index of a coin in the list of coins
listcoins Making a list of the tendered coins
itemdisplay Determining which image to display given an index of an item in the list of items for sale
denomdisplay Determining what text to display given an index of a coin in the list of coins
displaycurrency Determining how to display a given quantity of money that is expressed in pounds
pricedisplay Determining what price to display given an index of an item in the list of items for sale
mkstr Displaying a non-zero integer as a string whilst displaying zero by the empty string

The following agents are used to perform actions:

coin[1-8]picMove The mouse click actions for selecting/deselecting coins
item[1-6]picMove The mouse click actions for returning selected items
item[1-6]pic0Move The mouse click actions for selecting items