tostring bug when using Python 3.9

[corb5309]

intelhex/intelhex/compat.py

Line 60 in 9769d3f

array_tobytes = getattr(array.array, "tobytes", array.array.tostring)

tostring has to become tobytes for this to work in Python 3.9, likely in versions before this as well.

Can confirm this issue on Python 3.9.

Traceback if necessary:

Traceback (most recent call last):
  File "/Users/ashley/Library/Python/3.9/bin/solo", line 5, in <module>
    from solo.cli import solo_cli
  File "/Users/ashley/Library/Python/3.9/lib/python/site-packages/solo/__init__.py", line 15, in <module>
    from . import client, commands, dfu, helpers, operations
  File "/Users/ashley/Library/Python/3.9/lib/python/site-packages/solo/client.py", line 27, in <module>
    from intelhex import IntelHex
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/intelhex/__init__.py", line 44, in <module>
    from intelhex.compat import (
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/intelhex/compat.py", line 60, in <module>
    array_tobytes = getattr(array.array, "tobytes", array.array.tostring)
AttributeError: type object 'array.array' has no attribute 'tostring'

[fernandez85]

tobytes was introduced in ver 3.2, and since then tostring is deprecated alias for tobytes
current implementation isn't ready for situation when it's completely removed, and that what happened in ver 3.9

[MaximumSU]

@fernandez85 i think, the fix is simple.
array_tobytes = getattr(array.array, "tobytes", array.array.tostring)
to:
array_tobytes = getattr(array.array, "tostring", array.array.tobytes)

[fernandez85]

I was thinking about this at first time, but then same problem will be with python ver 3.0.x, and 3.1.x. I know there shouldn't be many users of these versions, but best way is to make it right :)
This should do the trick (in that exact place):
array_tobytes = array.array.tobytes if sys.version_info[1] >= 2 else array.array.tostring

or use hasattr

[MaximumSU]

getattr(array.array, "tostring", array.array.tobytes)

array.array.tobytes if sys.version_info[1] >= 2 else array.array.tostring

IIt does't matter, the result is the same. But for me is interesting:

@fernandez85 I was thinking about this at first time, but then same problem will be with python ver 3.0.x, and 3.1.x.

Why? All python < 3.9 has "tostring", for python >=3.9 it will use the default as "tobytes".