Laszlo Pandy

Since I am the person who manages the money for our house, I need an efficient way to keep track of our expenses and an easy way to calculate who owes what to whom at the end of the month. There are lots of good free software utilities for managing money like GnuCash, KMyMoney and the wonderful Gnumeric spreadsheet. I had been using Gnumeric to manage the money for the last 8 months, but now that we have some people staying at the house for just the summer, and other leaving and coming back in September, the spreadsheet was not able to adjust to these irregular circumstances.

The reason I decided to write my own application from scratch instead of using an already existing money management application was because my problem is multi-person orientation and most (if not all) of the money management programs I have tried are single-person oriented. For example GnuCash will let you setup accounts that show you all the money moving to and from a single person. But in my house things like food are paid by any person and shared by every other person. Thus to efficiently and easily calculate who owes how much, it must take into account the fact that one pizza may be paid for by one person, but it was eaten by 4 people. Also I don’t want to have to divide up the amounts myself and put it into GnuCash with multiple accounts, because then I might as well be doing it on paper.

I could have spent my time learning to make an already existing application do exactly what I want; and I probably would have found something pretty close. But I decided that it would be faster to just program it from scratch and then I would be sure I would get exactly what I wanted. I think I was right; it took less then 2 weeks to finished writing this program.

The program is currently called ‘Adventure Money’, but if anyone can think of a better name for it let me know and I’ll gladly change it.

When you first launch the program you will see it has five views, all of which can be seen in the screenshots below.

• The ‘Money Owed’ view which shows you a list of all the people and how much money they owe this month.
• The ‘Summary’ view which shows you a break down of the values in the ‘Money Owed’ view by each category and each item.
• The ‘Payments’ view which shows you all the payments or bills in the account and lets you search them quickly.
• The ‘Categories’ view which shows you all the categories of payments and lets you create new ones and edit older ones.
• The ‘People’ view which lets you create, delete and change the name of people as well as set the manager of the account. The manager is the one that everyone will give money to (or take money away from) at the end of the month.

Now I will create an example account:

Here you can see that I have created an account with 3 people, and I am the manager. You can rename a person inline by clicking on the row.

In this screenshot we are creating a category. The category is rent, and is paid by me. Obviously everyone shares the rent, because they all live in the house. But this program does not have to be used by people who live together, only by people who shared money.

I have also created another category ‘Food’ which is paid by anyone. Since I have not specified here who will pay for it, it must be specified when a payment is created. Categories do not have to have a payee, but they do have to have a list of people that shared it.

Here you can see I am entering the rent as a new payment. The value is $900, the date is the 1st of the month, and the category is ‘Rent’. Since I have specified the category, I cannot change the ‘Paid By’ and ‘Shared By’ fields. If I select no category then I can specify the payee and the sharers.

Here is a little popup of the GTK+ Calendar widget to let you select the date. Unfortunately making the popup disappear if you click outside it is only possible with C code and not python. This means that you have to click the close button below to make it disappear.

Now you can see the payment in the list. If I had lots of payments here I could use the widgets above to narrow down my list or search for a specific payment.

Here in summary view you can see everything that a specific person paid for and shared in each month. Currently we have all years and all months selected, and we can see that Eric shared $300 of the rent ($900 split three ways).

Here we can see that I have also shared $300 of the rent and I have paid $900 for rent.

In the money owed view for May 2007 we can see that since we all shared the $900 rent, and there are three of us, we each pay $300. Since I paid for the rent out of my own pocket and $300 of it is my share, I am owed $600. Since I am the manager I so not get displayed in the list but you can see how much I am owed in the text at the bottom.

To show you how the program can handle any expense by any person lets create a payment that wouldn’t normally factor into the monthly costs of a house. Rody bought some pizza one day for $30 and Eric ate some too. Normally it would be easier for Eric to just give Rody $15 in cash, but if we just create a new payment of $30 that is paid by Rody and shared by Eric and Rody it will all get consolidated into their end of the month payments.

Now we go back to ‘Money Owed’ view and we can see that under ‘Paid This Month’ for Rody is says $30. Also notice that since I was not involved with the pizza transaction I am still owed a total of $600. The only difference is that $15 has been added to how much Eric owes and $15 has been subtracted from how much Rody owes. This is effectively a $15 payment from Eric to Rody. In a similar way this program works really well even for people who don’t live together but who visit a restaurant as a group and only one person picks up the bill.

You may also notice the error value in the bottom right corner. All math is performed using the Python decimal module so that there are no binary representation errors when storing the values as floats, but there will still be some error when you divide a $20 payment by 3 people. However the error should never be more than a cent.

The program is written in Python its dependencies are:

• PyGObject (for event notification)
• PyGTK (for the GUI)
• Python Glade2 (for loading the GUI)
• XML Minidom for Python (for loading and saving files)
• Python decimal (for base-10 math)
• Python datetime module (for date calculation)

That’s it for now folks. If you want to use this program or even improve it, just drop me a line, or leave a comment on this page. I would love to hear from you if anyone finds this as useful as I do. You can download the Python source to run or to change the program (please send me patches). As always the code is licensed under the GPL.

I just finished writing my money managing application which I will post on my blog soon. This application has five separate views that can be switched in the main window like the “workspaces” in Jokosher. However I didn’t want to restrict myself to only looking at one of these views at a time, so I put in the option to create a new window that does not have any toolbars or menus, just the view switcher. This means that there could be any number of GUI instances looking at my program’s model at the same time. There could be two copies of the same view and when one is updated and other one has to reflect the changes.

I have implemented my listener code using Python’s GObject bindings so that all the views can know when a signal is emitted on the model. However if there are many views all running at the same time, sending a GObject signal takes a long time. If a signal is sent in response to a button being clicked, the button will stay pushed down for a few seconds while it waits for the signal emission to return. This makes the application look slow and unpolished. I decided that it doesn’t matter if not all the views are updated immediately; I’d rather have the button come back up and then have everything update. So I made this little class to do exactly that:

import gobjectclass AsyncGObject(gobject.GObject):       def __init__(self):               gobject.GObject.__init__(self)

       def emit(self, *args):               gobject.idle_add(gobject.GObject.emit, self, *args)

Just subclass this class instead of gobject.GObject and all your signals will be asynchronous.

There’s not a lot of these tech or open-source conferences in my area. The only ones I can list off the top of my head are the Ottawa Linux Symposium (but that’s only hard core kernel stuff) and the Desktop Developers Summit, and both of those cost quite a bit of money.

So I get really excited when some cool, free (as in beer) and collaborative conference happens. This Saturday there will be a BarCamp at my university. In fact it will be in the same room I had linear algebra in only two hours ago. Usually I wouldn’t look forward to going to school at 8:30 (!) on a Saturday morning, but this is a special occasion. I don’t think any one in Ottawa will read this, but if you are from Ottawa put a comment on my blog so I at least know you exist. The details and schedule are on the BarCamp wiki.

At the beginning of this year I was sitting in my dorm room listening to LugRadio, thinking about how awesome the open source community was and how much I wished to be a part of it. Up until that time my entire open source contribution amounted to a few patches and bug fixes with Amarok. I imagined what it would be like to help out the community, get kudos from everyone online, and piss my pants laughing with the dudes from LugRadio.

It’s not that I couldn’t contribute. I had two years of Java experience from high school, but I had no idea how to do C++ so I struggled when trying to make a difference hacking on Amarok. I also went the Ubuntu Breezy Summit in Montreal and tried to join the Ubuntu Documentation Team, but I didn’t have the initiative to start writing something on my own. It seemed much too difficult to start contributing even though I had novice programming skills.

In March 2006, Jono mentioned on LugRadio that someone had started the code for his JonoEdit idea. He also mentioned that they desperately needed contributors to write code in Python, and that everyone should come on board now while the code was small and easy to learn. I already knew Python and it was my favourite language, so I took his advice.

I only mention this now because back then I never would have thought that in less than a year I could go from writing useless Python scripts on a Saturday morning, to being hated and envied by the massively hilarious dude I hear every second Monday morning. In my book, that’s quite an accomplishment.

I guess my point is that no matter how hard you have tried to contribute and integrate yourself into a new community, and no matter how many times you feel like you have been rejected, all you have to do is keep moving until you find your passion and it will be smooth sailing after that. It turns out my passion is programming in Python, and now I’m responsible for a large part of Jokosher.

There has been a lot of talk lately about Ubuntu Feisty including non-free components by default. While I believe that non-free is bad, the Ubuntu guys have the chance to make the situation a lot better for new users. Currently new Linux users who depend on hardware that only has proprietary drivers will blame Linux for not working with their system. There is no way to tell the user that if they bought hardware with open drivers it would work. Instead they are just left in the dark and the new user comes away with a bad impression of Linux.

I’ve heard a lot of people say that if we educate people about free software then they will understand the difficulties we are having and can make the right choice next time they buy hardware. They may still use binary drivers, but at least they will be using Linux, and a few small steps in education can go a long way.

If you have been following Windows Vista, you may know that it will include a feature called “Windows Performance Index”. This is supposed to give the user a single number that represents the capability of their system. This is especially important now that Intel has decided to stop putting megahertz numbers in their chip names. If it can be boiled down to a single number, it will be a lot easier for the average user to understand. Here is a screenshot of this feature in action.

My idea is to do the same thing except for free software:

As you can see, at the top of the window there are links to help pages that discuss various issues about free software. Then there is a list of all the known software packages installed on your system that have restrictions of any kind. Beside that is a gigantic number which is your Free Software Index. Right now its just the number of packages you having installed, but there could be different values for packages with patent vs. non-free issues and drivers vs. regular software. At the bottom there is a refresh button, which would search for more non-free software and a close button.

You could also have a button next to the package names which describes what it does, and what (if any) free equivalents are available, as well as an uninstall button for each package. This would be awesome to see in the next Ubuntu so that if it comes with non-free software by default, you could quickly know which packages they are, decide if you absolutely need them, and quickly uninstall them if you don’t.