In a previous blog post I mentioned the possibility for using non ASCII characters as part of identifiers. Nils Langner, who runs the German "PHP hates me (but that's ok)" blog, then wondered whether it makes sense to use German (in his case) terms for identifiers in code in the comments it was also discussed what language is best to be used in comments.

The argument for using only English is simple: Every developer should know at least basic English and using English helps when either outsourcing, opensourcing or reaching new markets.

Now there are arguments against English, too, one is that not all developers are able of using English properly so reading and writing comments is more difficult for them - now you don't have to write long prosaic texts in comments, but still ...

The other argument goes by domain-specific terminology. In some cases - for instance when bound to legal environments - such terms can't be translated properly. For instance when dealing with financial data accounting by US-GAAP differs in many parts from the German accounting rules: For some positions you find translations which have the same meaning but are calculated slightly different so using the English term would imply the values would be calculated by the US rules (sorry British folks for this example - I have no idea about the British terminology and accounting rules, but have basic understanding of German rules and US-GAAP ;-)). Ignoring this problem you still have to consider that you'd still talk German to your customer so the customer would use German terminology and you have to keep a dictionary for these terms which is a pain for everybody involved.

So now one could use mostly English with some local terms which gives a nice mixture ("function getEigenkapitalrendite()") or invent complete new terminology ("function erhalteEigenkapitalrendite()") which is stupid in comments, too ("The Eigenkapitalrendite is depending on the Gewinn and the Eigenkapital") ...

Now I'm in the "lucky" position that most things I do these days are either done for some American company or a popular world wide used open source project and is mostly about stuff where the typical terminology is English so I can use my bad English everywhere - but I'm curious what others are doing and what others think.