Storing a list of variables

ID:723668
 
May 4 2012, 11:14 am
Keywords: lists, variables
(See the best response by Stephen001.)
Problem description:
I've been working on a merchant system of buying/selling resources and the code length is getting too long. I know of a way to fix it, but I don't know if BYOND actually supports it.

I just want to store variables in a list and index the list rather than having to make a separate if statement for each resource just because I have to put in that resource's unique variables for price and quantity. Is this possible?
May 4 2012, 12:36 pm (Edited on May 4 2012, 12:42 pm)
The answer to your question is basically "Good God, yes it is. And a much better way of handling merchants."

I assume what you are doing at the minute is something like this?

if <oneitem>
   Show the price, ask if they want it
if <a different item>
   Show the price, ask if they want it
if <a different item>
   Show the price, ask if they want it
if <a different item>
   Show the price, ask if they want it


An easier way to do this without the use of multiple if statements and lengthy code is;

-Show the user a list of things the merchant sells.
-Optionally, make this list include pricing (have the list contain [item.name] coupled with [price].)
-When the user picks an item from the list, do your input() statement asking if they'd like to buy it.
-Deduct the gold if so, otherwise return to the list or exit the merchant.


You'll want to use a for list proc followed by Input() to accomplish what your many, many if statements are doing.
May 4 2012, 2:09 pm
Thanks for your reply, Death.

var/b=input("Which resource do you want to buy?") in rlist
                            switch(b)
                                if("plastic level 1")
                                    var/c=input("How much of the resource do you want to buy?") in list ("One cargo bay","Two cargo bays","Three cargo bays","Cancel")
                                    switch(c)
                                        if("One cargo bay")
                                            for(var/obj/consoles/merchant_database/M)
                                                if(M.z==usr.z)
                                                    usr<<"price: [M.pl1p]"
                                                    if(M.pl1p>tcredits)
                                                        usr<<"<font color=red><b>Not enough credits to purchase this item!</b></font>"
                                                        return
                                                    else
                                                        if(M.pl1q>=1)
                                                            if(c1slots.len>=1)
                                                                if(c1contents.len==0)
                                                                    for(var/obj/c1 in c1slots)
                                                                        var
                                                                            i=0
                                                                            selection
                                                                            type
                                                                        for(i=1,i<=1,i++)
                                                                            selection = rlist[i]
                                                                            type = rlist[selection]
                                                                            var/obj/O = new type ()
                                                                            c1contents.Add(O)
                                                                            O.loc=c1.loc
                                                                    spawn(3)
                                                                        M.pl1q--
                                                                        M.pl1p=round(M.pl1p*1.1,1)
                                                                    for(var/obj/consoles/ships_computer/S in world)
                                                                        if(S.z==usr.oz)
                                                                            S.credits-=M.pl1p
                                                                            spawn(1)
                                                                                usr<<"You now have [S.credits] credits left."
                                                                                break
                                                                    usr<<"Thank you for purchasing [b]."
                                                        else
                                                            usr<<"<font color=red><b>Sorry, but there is not enough in stock to buy that item.</b></font>"
                                                            return


The problem isn't much with the organization as it is with the variables. I have separate merchant "databases" that store the quantities of items and their price. The price goes up or down slightly depending on if people are buying or selling it.

The issue is that all these different resources have a price variable and a quantity variable, and I've been putting them in for each resource, but I was wondering if its possible to put them in a list and get the variables that way.
May 4 2012, 2:54 pm
Best response
You really want some datums for this.

Basically, have a bunch of "Product" datums, each for the kind of product that needs selling/buying:

Product
    var
        item_name
        item_type
        quantity
        price

    proc
        sell_product(var/mob/player/P)
            P.credits -= src.price
            var/item = new item_type()
            P.contents.Add(item)
            item.loc = src.loc
            src.decrease_quantity()

        decrease_quantity()
            src.quantity--
            src.price = round(src.price * 1.1)

        can_be_bought(var/mob/player/P)
            return src.quantity > 0 && src.price <= P.credits

// An example.
obj/vendor
    var/list/warez = new()

    New()
        ..()
        var/Product/plastic = new()
        plastic.item_name = "Plastic"
        plastic.item_type = /obj/plastic
        plastic.quantity  = 100
        plastic.price     = 10
        warez[plastic.item_name] = plastic
        var/Product/wood = new()
        wood.item_name = "Wood"
        wood.item_type = /obj/wood
        wood.quantity  = 100
        wood.price     = 10
        warez[wood.item_name] = wood

    verb
        what_are_you_buyin()
            set src in oview(1)
            var/mob/player/P = usr
            var/choice = input("What are you buyin'?") in warez
            var/Product/chosen_product = warez[choice]
            if (chosen_product.can_be_bought(P))
                chosen_product.sell_product(P)
                usr << "Much obliged to ya sir!"
            else
                usr << "You are poor."
                view(10) << 'you_are_poor.ogg'


Basically the datums store all pertinent data to a specific stock of a product, for a particular vendor, and controls it's own pricing. The vendor then just needs a list of these.
May 6 2012, 1:57 pm
Thanks, Stephen! I didn't think to do it that way at all. It took me a while to wrap my head around what you were doing but I got it now.