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Comment by berkes | Hacker News Reader

In my last financial product we added 'bitcoin' and 'festival tokens' as currencies in the backend. At first for fun.

But we found out the client devs (web, mobile apps) had severe difficulties and wanted it removed. Turned out they all implemented currencies wrong. Either with hardcoded decimals or with localised in and outputs that would break if a client changed their locales.

So now, my favorite best practice for any financial data handling is that: ensure your system can handle Bitcoin (8 decimal places) and festival tokens (missing currency symbol, zero decimals). Anywhere this leads to trouble is a red flag and will probably cause trouble later on. Now at least you are aware.

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That's great advice. I'll add it to my list of round-tripping German, and Japanese text with emojis, and changing the timezone.

What do you mean by round tripping German here?

I think I get the issues with the other two, but curious about the first thing!

Not sure about round tripping but perhaps the longer words might stress test webpage layouts.

Round trip = sending it from the input/front end into the system/back end (whatever it is, database/file system/???) and back to the front, to confirm that what comes out is what you put in.

For German, I'd assume it's just about the special characters (äöüß), ie testing that encodings are somewhat correct (at least beyond ASCII).

I was talking to a dev this weekend about i18n and said he used German to test page layouts.

Yeah using German translations is a well known simple strategy to see how your site handles longer word length, because of the language characteristics.

It will do a good job of pointing out places where you haven't built in adequate flexibility for longer words. It's not perfect of course, there are times when a translated word is shorter, but it is a nice real world test of the basic flexibility of your page layout.

Spanish is also a very good choice for testing. I used it to see if a POS Terminal can handle the translations on small screens.

German has a (few?) instances where going from lowercase -> uppercase -> lowercase or view versa is ambiguous because there are multiple upper/lower variants for each letter. I also think one even changes the text length because it turns into two.

Yeah, a sibling poster shows this explicit example (from CPython IIUC) with Eszett/'ss'.

Yes thank you, didn't notice it posted before my comment.

    In [8]: "ß".upper().lower()
    Out[8]: 'ss'

I wonder if there's any notable currency where you have to support fractions. Like 1/3 of a "whatever".

Edit: Found the right search term. "Non-Decimal Currency". It's a thing, at least historically.

https://en.wikipedia.org/wiki/Non-decimal_currency

The US dollar inherits a mixed base-8 and base-10 system.

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