Schemdraw is not compatible with Python 3.7

[Former user]

From the documentation:

https://schemdraw.readthedocs.io/en/latest/usage/start.html

Schemdraw requires Python 3.7+. Python 3.8+ is recommended for its walrus operator (:=) that allows a more compact notation of defining schematics.

However, Schemdraw imports Literal from typing.py, which is not supported in version 3.7. Can document which versions of Schemdraw are 3.7 compatible?

[cdelker]

Reference: https://github.com/python/typing/issues/707

[Yossi Oren]

Hi, this breaks compatibility of Schemdraw with Google Colab, which is using a 3.7 runtime right now. Still works if I force version 0.8, as shown below.

!pip install schemdraw
import schemdraw
print(schemdraw)

‌

Collecting schemdraw
  Downloading  (82kB)
     |████████████████████████████████| 92kB 8.7MB/s 
Installing collected packages: schemdraw
Successfully installed schemdraw-0.10

---------------------------------------------------------------------------

ImportError                               Traceback (most recent call last)

 in <module>()
      1 get_ipython().system('pip install schemdraw')
----> 2 import schemdraw
      3 print(schemdraw)

---

 in <module>()
      3 from __future__ import annotations
      4 
----> 5 from typing import Literal, Type, Any
      6 from collections import ChainMap
      7 import warnings


ImportError: cannot import name 'Literal' from 'typing' (/usr/lib/python3.7/typing.py)


---------------------------------------------------------------------------
NOTE: If your import is failing due to a missing package, you can
manually install dependencies using either !pip or !apt.

To view examples of installing some common dependencies, click the
"Open Examples" button below.
---------------------------------------------------------------------------

‌

!pip install schemdraw==0.8
import schemdraw
print(schemdraw)

Collecting schemdraw==0.8
  Downloading https://files.pythonhosted.org/packages/87/c2/c64538e9213b7927da7cd797e3b77a32ddfb69c094b3c32eeac605f1e900/schemdraw-0.8-py3-none-any.whl (53kB)
     |████████████████████████████████| 61kB 4.7MB/s 
Requirement already satisfied: matplotlib in /usr/local/lib/python3.7/dist-packages (from schemdraw==0.8) (3.2.2)
Requirement already satisfied: numpy in /usr/local/lib/python3.7/dist-packages (from schemdraw==0.8) (1.19.5)
Requirement already satisfied: pyparsing!=2.0.4,!=2.1.2,!=2.1.6,>=2.0.1 in /usr/local/lib/python3.7/dist-packages (from matplotlib->schemdraw==0.8) (2.4.7)
Requirement already satisfied: cycler>=0.10 in /usr/local/lib/python3.7/dist-packages (from matplotlib->schemdraw==0.8) (0.10.0)
Requirement already satisfied: python-dateutil>=2.1 in /usr/local/lib/python3.7/dist-packages (from matplotlib->schemdraw==0.8) (2.8.1)
Requirement already satisfied: kiwisolver>=1.0.1 in /usr/local/lib/python3.7/dist-packages (from matplotlib->schemdraw==0.8) (1.3.1)
Requirement already satisfied: six in /usr/local/lib/python3.7/dist-packages (from cycler>=0.10->matplotlib->schemdraw==0.8) (1.15.0)
Installing collected packages: schemdraw
  Found existing installation: schemdraw 0.10
    Uninstalling schemdraw-0.10:
      Successfully uninstalled schemdraw-0.10
Successfully installed schemdraw-0.8
<module 'schemdraw' from '/usr/local/lib/python3.7/dist-packages/schemdraw/__init__.py'>

‌

[John Hagen]

As Guido says, if this package wants to support 3.7, it will need to depend on typing_extensions from PyPI and use that for types added later in Python’s lifetime: https://github.com/python/typing/issues/707#issuecomment-603972535

[John Hagen]

schemdraw only supports Python 3.8+ as documented in this commit: https://bitbucket.org/cdelker/schemdraw/commits/a69a692ff26cb4d7f6032c74472e4622951a27d6

[cdelker]

7227aae adds conditional import of typing_extensions. Also drops use of math.dist, a Python 3.8-only function. Everything appears to work in 3.7 now, with the exception of some documentation/test examples that use the walrus operator.

[John Hagen]

@cdelker Would you be able to publish a new release on PyPI that includes this and pull request #20? Thanks.

[cdelker]

0.11 released. fb2840e

[Yossi Oren]

Verified that Schemdraw now works on Google Colab:

!pip install schemdraw
import schemdraw
print(schemdraw)
 
Collecting schemdraw
  Downloading  (84kB)
     |████████████████████████████████| 92kB 6.4MB/s 
Requirement already satisfied: typing-extensions; python_version < "3.8" in /usr/local/lib/python3.7/dist-packages (from schemdraw) (3.7.4.3)
Installing collected packages: schemdraw
Successfully installed schemdraw-0.11
<module 'schemdraw' from '/usr/local/lib/python3.7/dist-packages/schemdraw/__init__.py'>

‌

Thanks a lot, John and Collin!