[Python-Dev] pathlib - current status of discussions (original) (raw)

Michael Mysinger cybersol at yahoo.com
Thu Apr 14 11:59:56 EDT 2016

Ethan Furman <ethan stoneleaf.us> writes:

On 04/14/2016 12:03 AM, Michael Mysinger via Python-Dev wrote: > In particular, one RichPath > class might return bytes and another str, or even worse the same class might > sometimes return bytes and sometimes str. When will os.path.join blow up due > to mixing bytes and str and when will it work in those situations?

What are you asking here? ... Meaning allowing os.fspath() and fspath to return either bytes or str will never cause the combination of bytes and str to work. Said another way: if you are using os.path.join then all the pieces have be str or all the pieces have to be bytes.

I am saying that if os.path.join now accepts RichPath objects, and those objects can return either str or bytes, then its much harder to reason about when I have all bytes or all strings. In essence, you will force me to pre- wrap all RichPath objects in either os.fsencode(os.fspath(path)) or os.fsdecode(os.fspath(path)), just so I can reason about the type. And if I have to always do that wrapping then os.path.join doesn't need to accept RichPath objects and call fspath at all.

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