[Tutor] I need help with my project

[Treyton Hendrix]

Awesome! Thanks to your help, I finally got my program done. Click here if
you want to see it! ---->

On Fri, Nov 30, 2018 at 5:14 PM Cameron Simpson <cs at cskk.id.au> wrote:

> Avi and Alan and Sibylle, you're making this a bit hard on the OP
> (Treyton).
>
> Yes he's supplied no context, but it is easy to make some suggestions.
> Each of yours suggests he design a much wider system (menu entry, web
> interface, some kind of GUI). All of which is (a) beyond him and (b)
> irrelevant.
>
> Why not pretend he _has_ the existing order, from wherever.
>
> Suggest ways to store that order (in a list, or a dict mapping ordable
> items to counts, or something). Then ask him to write a little Python,
> or even detailed English prose.
>
> Treyton: you seem to have recitied a homework question:
> >If the user selected a sandwich, french fries, and a beverage, reduce
> >the
> >total cost of the order by $1.00.
> >This is what I have to do and I don't know where to start.
>
> Ok, this is clear: Treyton can't get off the ground, very common for
> beginning programmers.
>
> The core challenge is to break your problem into a sequence of tasks.
> How would _you_, a person, do this if you had a food order given to you?
>
> Think about a food order. It is usually a list of standard food items, a
> count of how many of each. And each item will have a cost.
>
> The total cost is the sum of (each item's cost * its price * its count),
> for each item in the order. Or for all possible items, by presuming that
> unordered items just have a count of 0.
>
> So you need:
>
> A label for each item, so you can talk about it. You can just use a
> string for this, eg "sandwich" or "fries". Make the strings simple to
> start with to avoid spelling mistakes. You can always associate better
> names with the short strings later.
>
> You need a table of items and their costs. It is normal to make a
> mapping for this, such a Python's dict type. You can write dicts
> literally:
>
>   costs = {
>     "sandwich": 200,
>     "fries": 100,
>   }
>
> In the example above, I'm imagining you have dollars and cents, and
> making prices in cents.
>
> You also need a representation of the order, being the item type and the
> count. You could use a Python list for this. Example:
>
>   [ "fries", 2 ]
>
> The whole order might be a list of those, example:
>
>   [ ["fries", 2 ], [ "sandwich", 3 ] ]
>
> So, a list of lists.
>
> For purposes of your program you can just set all this stuff up at the
> beginning, not worrying about GUIs or input forma or any complication.
>
>   whole_order = [
>     ["fries", 2 ],
>     [ "sandwich", 3 ]
>   ]
>
> Now comes the part you need to do:
>
> - write some Python code to compute the total cost of the order (item
>   cost * item count), summed for all the items. Print this raw total so
>   that you can see it is correct.
>
> - write some totally separate code to look at the order and decide if
>   the client met your special condition (sandwich, fries, beverage) and
>   get a true/false result. Print this, too.
>
> - write a Python statement to subtract $1.00 (or 100 cents) from the
>   total if that condition is true. Print that.
>
> Then fiddle the order and run your programme several times to check that
> it is behaving the way it should.
>
> If you find difficulties you cannot surmount, come back here (by
> replying directly to one of the messages in your discussion) with:
>
> - your complete code
>
> - your expected output, and the output from your programme
>
> - a complete transcript of any error message, for example if your
>   programme raised an exception
>
> Make sure these are inline in your message, _not_ attachments. We drop
> attachments in this list.
>
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
>