Py2 vs. Py3 incompatibility: TypeError

Situation

I’m confused by the statement in the Readme that seems to say 2.10.0 does still support Python 2.7. That’s not what I’m seeing. I have a project that uses this package and runs in Py2, and as soon as it started using the 2.10 release, I started getting errors like this which look to me like what you’d get from a Py2 vs. Py3 incompatibility:

TypeError("Expected str or VersionInfo instance, but got <type 'unicode'>"

When I pin the dependency to <2.10, the error goes away.

_Originally posted by @eli-darkly in https://github.com/python-semver/python-semver/issues/161#issuecomment-654455352_

[tomschr]

Thanks Eli! Actually I found an example:

$ python2
>>> import semver
>>> semver.compare("1.1.0", u"1.2.2")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "semver.py", line 100, in wrapper
    return func(*args, **kwargs)
  File "semver.py", line 779, in compare
    return v1.compare(ver2)
  File "semver.py", line 427, in compare
    cls.__name__, type(other)
TypeError: Expected str or VersionInfo instance, but got <type 'unicode'>

This is a bug, of course, and shouldn’t happen.

[tomschr]

Thanks @gsakkis for your ideas. 👍

to be honest I’d either drop python 2 support

That was also my thought at first. However, I think it would make sense to have this fix in semver2 too.

or use six as a dependency instead of copy-pasting parts of it.

I was thinking about six, but I would like to avoid introducing another dependency. Especially if this development line (semver2) will be deprecated soon and we will switch to semver3.

The parts that are coming from six are really very small. All in all it’s ~23 lines of code. It’s probably easy to remove them once we release semver3.