Came to mention GError as well. I actually use the GError implementation/style to auto-bind GObject based classes to Spidermonkey JS exceptions in a homegrown g

Came to mention GError as well. I actually use the GError implementation/style to auto-bind GObject based classes to Spidermonkey JS exceptions in a homegrown generic JS binding layer (not unlike GObjectIntrospection, which came about much later). When everyone uses this style it doesn't really get in the way, even when used from C, and prevents cases where APIs don't return proper error info. Everyone just gets used to putting the error parameter last. (And code generators are especially good at it :))