Re - Contradictory error messages in Python 3.4 - standard library issue!

[Matt Wheeler]

On Thu, 16 Jun 2016, 23:31 Harrison Chudleigh, <
harrison.chudleigh1 at education.nsw.gov.au> wrote:

> Sorry! I was trying to indent a line and accidentally sent only half of the
> message.
>

It would be helpful if your reply was actually a reply to your previous
message, to enable us to follow the thread of the conversation.

As I was saying, I changed the line and reran the program. However, this
> produced another group of error messages. One was -
>

>From what, to what? Just showing us stacktraces means we have to guess at
the problem.

File
>
> "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/tokenize.py",
> line 438, in open
>     encoding, lines = detect_encoding(buffer.readline)
>   File
>
> "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/tokenize.py",
> line 409, in detect_encoding
>     if first.startswith('BOM_UTF8'):
> TypeError: startswith first arg must be bytes or a tuple of bytes, not str.
> So, first the interpreter says startswith() takes strings, now it says it
> takes bytes? What should the module be doing?
>

The reason you're getting seemingly contradictory error messages is that
`.startswith()` is a method which belongs to the `first` object, and that
object is a different type between the first and the second time it's
called.
Both the `bytes` and `str` types have a `startswith` method, but each one
(understandably) only accepts an argument of the same type.

Without actually seeing your code I can't guess what the cause of that is,
but perhaps you need to decode a `bytes` object to a `str` or encode the
other way around.