[Tutor] Python Assignment

[Alan Gauld]

On 03/08/16 18:58, Justin Korn via Tutor wrote:

> This is what I have so far:

OK, This is starting to look a bit random.

You need to slow down and work through what is happening
in each method and especially what data is being passed
around where. At the moment it makes no sense whatsoever.

> def load_file():
>     with open("warehouse_data.txt") as infile:
>         for line in infile:
>             data = process_line(line)

Where is process_line defined? And what happens to
data? At the moment its a local variable that
disappears when load_file terminates.

> class Order():
>     def __init__(self, order_number):
>         self.order_number = order_number
> 
>     def add_item():
>         order = []
>         order.append()

What do you think this does?
It takes no input values and appends nothing(*) to
a list that is deleted at the end of the function.
I'm pretty certain that's not what you want.

(*) In fact append will error because it needs
an input value.

>     def sort_key():
>         all_keys = []
>         for item in self.order_number:
>             all_keys.append(item.sort_key())
>         return min(all_keys)

You are looping over self.order_number.
What kind of data is order_number?
What kind of data will item be?
Does item have a sort_key() method?

Also neither function has a self parameter so will
not be usable methods of the class.

> class LineItem():
>     def __init__(self, orderNumber, partNumber, quantityNumber, aisleNumber, shelfNumber, binNumber):
>         self.orderNumber = orderNumber
>         self.partNumber = partNumber
>         self.quantityNumber = quantityNumber
>         self.aisleNumber = aisleNumber
>         self.shelfNumber = shelfNumber
>         self.binNumber = binNumber
> 
>     def sort_key():
>         p = (self.aisleNumber, self.shelfNumber, self.binNumber)
>         for i in p:
>             p.sort(i.sort_key())
>         return(self.aisleNumber, self.shelfNumber * -1, self.binNumber)

Look at what the loop is doing.
It iterates over three values and tries to sort the tuple
p based on a sort_key method of each value.
But do those values have a sort_key() method?.
And does sorting p achieve anything?

I assume you didn't try running this code since it would
result in errors. You need to sort out the data types and
use them consistently.

-- 
Alan G
Author of the Learn to Program web site
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