nestedContainer in KeyedEncodingContainer and UnkeyedEncodingContainer should be throwing

[cherrywoods]

@tonyfreeman

If you mean Encoder’s errors - it is an implementation detail, and this information can be put in the error itself. Encodable errors - you’re already in control and can figure out on what step you got an error.

I mean concretely EncodingError. I'm not sure if this is what you mean with Encodable errors, but in case of EncodingErrors, you are indeed not in control (in understanding of control flow). Sure when you are debugging you know it, but in code when you are using e.g. JSONEncoder you do not directly know where the error comes from because it is passed from one encode(to:) implementation to the next via the method calls inside the encoder (you kind of passed the "control" to the encoder implementation). So you could of course also provide this information yourself there, but only in your own types, not Array, and therefor it is necessary for this in my understanding.

@tonyfreeman

This is also a hack, so this will do as well:

if "(type(of: encoder))" == "_JSONEncoder"

I don't think this is a hack, I got it from there:

@itaiferber

At the moment, the right way to do this would be to pass a known value through the JSONDecoder's userInfo (which you control) and check for that type through decoder.userInfo. (There’s also currently no way to query a decoder for its format, so the solution there is the same. One of the enhancements I want to make is along this vein, to improve the ergonomics of checking this.)

It at least works better IMO, because this is an internal name and there is no guarantee that it won't change. If you think about a closed source Encoder with hidden implementation, it will definitely be harder to guess the name.