I have been using the C# question type as provided here: http://coderunner.org.nz/mod/forum/discuss.php?d=79
using the steps to create a question type here: http://coderunner.org.nz/mod/book/view.php?id=193&chapterid=749
However, I am running into the issue where I can save the new question type and have it displayed in the question types dropdown, however, if I go to create a new question with the custom question type I get the error:
"Error loading prototype: Error fetching prototype. qtype_coderunner/Prototype DEMO_C_VIA_PYTHON is unavailable in this context, or does not exist."
The original question I created the question type for, works perfectly, however I can not create any more questions using the question type.
If any more information is required, please ask.
I had this issue as well but it was only a matter of renaming the prototype.
It somehow depended on the right timing of renaming and using the prototype.
I got this working after some trying but can not remember the steps I followed to solve that naming conflict.
This sounds like it might the bug that I became aware of earlier this week via another forum posting: you can create question types with names containing any characters you like but when you try to use them, non-alphanumeric characters are filtered out of the requested type name. This results in "Error fetching prototype."
So perhaps try a type name like 'csharp_function' rather than 'c#_function'?
The fix I have in my development system is to constrain question types to be alphanumeric when you first create the prototype, but I'm starting to wonder if I shouldn't instead allow arbitrary white-space trimmed strings.