Skip to Main Content
Python Programming On Win32
book

Python Programming On Win32

by Andy Robinson, Mark Hammond
January 2000
Intermediate to advanced content levelIntermediate to advanced
672 pages
21h 46m
English
O'Reilly Media, Inc.
Content preview from Python Programming On Win32

Coding Transactions

Now it’s time to design a core object model. The module transac.py defines a Transaction class that captures the key notions we covered earlier. It also goes somewhat further; we’ve used Magic Methods to define a basic algebra of accounting. The class construction is straightforward. However, first we need to mention three design issues. Since this is a contrived application, we’ve gone for simple solutions that are good enough for our needs; for a proper accounting system, the solutions would be different.

  • The first issue is how to represent the tree structure behind a company’s accounts. After several years of experimenting with different designs, it’s clear that simple strings do the job nicely. Thus a cash account can be represented with a string like MyCo.Assets.NCA.CurAss.Cash.MyWallet. This reduces lots of complex tree operations to simple string functions; finding the sum of all cash accounts becomes trivial. It should of course be hidden in the user interface to save end users from typing, but it clarifies the data structure.

  • The second issue is how to keep the balance sheet in the right order as shown in Figure 6.3. You’ll see that the accounts were named in alphabetical order at every level; we cheated and used 1_NetAssets and 2_Capital at the top level to force an alphabetical order. This hack keeps our tree in the conventional balance sheet order without needing any extra sort fields. The display account names used in reports (or indeed a GUI) could ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Advanced Python Programming - Second Edition

Advanced Python Programming - Second Edition

Quan Nguyen

Publisher Resources

ISBN: 1565926218Supplemental ContentErrata Page