On Wed, Apr 6, 2011 at 9:04 PM, Brad Bailey <computer_b...@yahoo.com> wrote:
> I dont understand why this is such a big deal. Nor do i understand why google
> can't find a reasonable answer. If one can't figure out from the title what
> I'm trying to do, then a look at code should firmly plant the intent. The
> general idea of the code is, in my opinion, very basic.
>
> I notice, that when you are coding a class instance, it's in the format of:
> newInstance = someClass()
>
> OK, so we are calling someClass as if it's a function. Is there a way to do
> something to the effect of:
> someClass(newInstance)
I fail to understand what that line of code is supposed to accomplish
or how it relates to your titular question.
> I've seen all kinds of hacks and workarounds that seem 10 times more
> complicated that this ought to be.
>
> class inventoryItem:
> itsDecrtiption = None
> itsVendor = None
> itsCost = None
> itsMarkup = None
> itsQuantity = None
That's defining class variables (Java lingo: "static" variables),
*not* instance variables. You want:
class InventoryItem:
def __init__(self, description, vendor, cost, markup, quantity):
self.description = description
self.vendor = vendor
self.cost = cost
self.markup = markup
self.quantity = quantity
Or using collections.namedtuple:
from collections import namedtuple
InventoryItem = namedtuple('InventoryItem', "description vendor cost
markup quantity".split())
# See http://docs.python.org/library/collections.html#collections.namedtuple
You would make a new instance of InventoryItem based on console user
input like so (ignoring input validation / error checking):
desc = input("Description: ")
vend = input("Vendor: ")
c = float(input("Cost: "))
m = float(input("Markup: "))
qty = int(input("Quantity: "))
newItem = InventoryItem(desc, vend, c, m, qty)
Exploiting dynamism can eliminate most of the redundancy, at the cost
of simplicity:
def identity(x): return x
fields = "description vendor cost markup quantity".split()
converters = [identity, identity, float, float, int]
newItem = InventoryItem(*[converter(input(field.title()+": ")) for
field, converter in zip(fields, converters)])
Cheers,
Chris
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