Not working with python 3.8.2 and from __future__ import annotations

[egh]

To reproduce:

$ mkdir test-jsons
$ cd test-jsons
# Set up dependencies, e.g.
$ cat > pyproject.toml <<EOF
[tool]
[tool.poetry]
name = "test-jsons"
version = "0.0.0"
description = "test jsons"
authors = ["Erik Hetzner"]
[tool.poetry.dependencies]
python = "==3.8.2"
jsons = "*"
EOF
$ poetry install
$ cat > test.py <<EOF
from __future__ import annotations
import jsons
from dataclasses import dataclass
@dataclass
class Foo(object):
    bar: str
print(jsons.dump(Foo('baz')))
EOF
$ poetry run python test.py

Expected output:

{'bar': 'baz'}

Actual output:

/home/egh/.cache/pypoetry/virtualenvs/test-jsons-Z5_mcWPc-py3.8/lib/python3.8/site-packages/jsons/_common_impl.py:42: UserWarning: Failed to dump attribute "baz" of object of type "Foo". Reason: 'NoneType' object is not callable. Ignoring the attribute. You can suppress warnings like this using jsons.suppress_warnings().
  warnings.warn(msg_, *args, **kwargs)
{}

Removing the from __future__ import annotations line fixes the issue.

[ramonhagenaars]

The issue seems to be that when using from __future__ import annotations, the type hints are converted to strings which makes jsons fail to find the right (de)serializer. I consider this a bug and it will be fixed and deployed in the next release.