ImportError: cannot import name 'VersionInfo'

[anirudhdpai]

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Describe the bug
Importing VersionInfo in the operators.py file gives out an import error since semver has deprecated VersionInfo and replaced it by Version

To reproduce
Run operators.py file from launchdarkly repo.

Expected behavior
Importing VersionInfo must be successful from launchdarkly

Logs

    from .client import *
  File "/usr/local/lib/python3.6/dist-packages/ldclient/client.py", line 18, in <module>
    from ldclient.flag import EvaluationDetail, evaluate, error_reason
  File "/usr/local/lib/python3.6/dist-packages/ldclient/flag.py", line 12, in <module>
    from ldclient import operators
  File "/usr/local/lib/python3.6/dist-packages/ldclient/operators.py", line 8, in <module>
    from semver import VersionInfo
ImportError: cannot import name 'VersionInfo'

SDK version
Latest version

Language version, developer tools
Python 3.6.9 and 3.6.15

OS/platform
Ubuntu 18.04 and 20.04

Additional context
https://readthedocs.org/projects/python-semver/downloads/pdf/latest/

[eli-darkly]

It's unclear to me how this could be happening. It looks like perhaps you have installed the prerelease 3.0.0-dev.2 or 3.0.0-dev.3 version of semver— the docs you linked to are for 3.0.0-dev.3. But the SDK's dependency on semver specifically requires that the version be less than 3.0.0. You'll see in our requirements.txt:

semver>=2.10.2,<3.0.0

[eli-darkly]

I'll add that "Run operators.py file from launchdarkly repo" is not really a usable instruction for reproducing the issue. Any given source file like operators.py does not get run by itself in isolation; import errors like you're seeing are dependent on the state of the overall Python environment, i.e. what packages have been installed. We do have unit tests in the repository that exercise all of the code in the SDK, including operators.py, and they are working fine; but they rely on having correctly installed the dependencies that are configured in our requirements.txt. That should happen for you automatically if you're using the LaunchDarkly SDK in an application, but I don't know anything about what your project may be or how you have set up your dependencies or development environment.

[anirudhdpai]

Looks like this is happening due to the packages we've got in our requirements.txt.

Thanks a lot for the input,
anirudhdpai