Currency Selection

How Flowing Pennies lets you choose a currency

by Bob Clark

originally published May 2008; last updated July 2010


There’s an old riddle that goes something like:

If someone who speaks three languages is trilingual...
and someone who speaks two languages is bilingual...
what’s someone who speaks one language?
An American.

C’est la vie, but this stereotype fits me perfectly. My lingua franca is English.

At this writing, the most common request for Flowing Pennies is the ability to use different currencies such as the British Pound £, the Japanese Yen ¥, or the Euro €. My personal experience (not) using different currencies mirrors my personal experience (not) speaking different languages. This is new territory for me; so this article is my way of articulating how it works, where I’m coming from, and how you and I can work forward from here.

There are many issues that come into play when considering the best way for a household finances application like Flowing Pennies to let you choose what currency it uses.

Just like the porridge in the story of “Goldilocks and the Three Bears,” software design is often a struggle to strike just the right balance between opposite extremes.

“Too Cold”

At one extreme, a finance application could just always show financial balances with the same numbers, and extract the currency from the system. So if you have your OS X system set for € it would always show the finances in euros. (Of course, if you then loaded that document on a Japanese system it might show the values in yen ¥.)

“Too Hot”

At the other extreme, a very sophisticated and complicated solution might be to allow each transaction to use its own currency. Maybe you pay for breakfast with dollars $ and lunch with euros €. But Flowing Pennies is designed very fundamentally to show a running tally of your household finances, as a single number.

So if different transactions within a document are using different currencies, suddenly conversion between currencies would be required.

But currency conversions fluctuate from day to day, or even from second to second. Trying to track your finances rigorously when the underlying ratios are varying so unpredictably is just asking for trouble.

(Hopefully) “Just Right”

Flowing Pennies 1.2 takes a middle approach. Now, when you create a new Flowing Pennies document, it defaults the currency to whatever your OS X system is set to. But if you bring up Flowing Pennies’ Preferences dialog, you can edit the currency for a given document. This makes it possible for one Flowing Pennies document to be tracked in dollars $ and another document to be tracked in euros € if that’s what you want.

One of the ways that Flowing Pennies keeps it simple is that there is no conversion between currencies. When you change the currency used for a given Flowing Pennies document, it only changes the format with which the values are shown.

Was this the right direction in which to take Flowing Pennies? The goal was to find a pragmatic balancing point between Flowing Pennies’ old behavior (which was, to paraphrase Henry Ford, “You can use any currency, as long as it’s dollars”) and a fraught-with-peril, overly-complicated potential currency conversion between any transactions.

Hopefully we found the sweet spot. Our euro-using and yen-using beta testers have reported satisfaction with Flowing Pennies’ implementation, but we are eager to hear your opinion. If you have suggestions or (especially!) complaints, please let us know.

Who knows what the future will be? Que sera sera.

Now that Flowing Pennies might use a currency without pennies, does its name even make sense any more? ¡Ay, caramba!

What will be the Clarkwood Software response to people who contact us about improvements and refinements to currency selection (and other features) in Flowing Pennies? Domo arigato.