When `nil` is coerced into `RArray`, it becomes `[nil]`

[matsadler]

When `nil` is coerced into `RArray`, it becomes `[nil]`

[matsadler]

So Ruby's C API has a bunch of functions to check a value is of a certain type (or convert it to that type with the implicit conversion methods, to_str, to_ary, etc).

There's some like rb_check_<type>_type that return the value if it's of that type, call to_<typ> if it responds to that method, or return nil if it can't be converted. Magnus looks for that nil and raises an error.

Then there's rb_str_to_str which returns the value if it's a string, calls to_str if the object responds to it, or errors if it can't be converted. This is convenient as then the code in Magnus doesn't have to do the extra nil check to return an error in the last case.

The array conversions are done using rb_ary_to_ary. Turns out this does not work like rb_str_to_str. Instead of erroring if the value can't be converted (or returning nil) it returns the value wrapped in an array.

In my defence, at the time I wrote this code the Ruby C API was totally undocumented (the headers now do document this potential confusion).

I've fixed this in 69ff299, but as it's a change in behaviour I'm going to put of releasing till 0.5.

[gjtorikian]

In my defence, at the time I wrote this code the Ruby C API was totally undocumented (the headers now do document this potential confusion).

No worries at all! Thank you for the project, I’m just calling what I see. 😄 Thanks for the quick fix!