[Python-Dev] Type hinting: TypeError: 'type' object is not subscriptable
Years ago, I fell in love with python and left C an C++ behind. Sometime later,
I fell in love with C# because with strong typing, my IDE does most of the work
for me - I never have to browse the API to find which method or attribute
exists in a class, I can use tab completion for everything, avoid type-o's,
etc. So I was recently thrilled to discover type hinting in python, and support
included in pycharm. I'm coming back to python now (for the last few months).
In python 3.6.1, and pycharm CE 2017.1.1 on windows (I haven't tested other
versions or other platforms):
The following is recognized and supported by pycharm, but then at runtime,
python throws an exception:
#!/usr/bin/env python3
def foo(bars: list[str]):
for bar in bars:
if bar.startswith("hi"):
raise
ValueError("bar should never say hi")
return True
if foo(["a","b","c"]):
print("Ok")
TypeError: 'type' object is not subscriptable
The problem is that python doesn't recognize list[str] as a type. Pycharm
handles it, and everything works fine if I'm using a non-subscripted type, like
plain old int, or str, or anything else.
Is this a bug, or is it something python simply hasn't implemented yet, or is
it something that's not going to be implemented?
Is there a workaround?
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Re: [Python-Dev] Type hinting: TypeError: 'type' object is not subscriptable
You should use List[int] (note capital first letter) and similar for other
generic types.
Please read https://docs.python.org/3/library/typing.html
The fact that this is accepted by PyCharm is a PyCharm bug, and should be
reported on their tracker.
--
Ivan
On 29 April 2017 at 14:32, Edward Ned Harvey (python)
wrote:
> Years ago, I fell in love with python and left C an C++ behind. Sometime
> later, I fell in love with C# because with strong typing, my IDE does most
> of the work for me - I never have to browse the API to find which method or
> attribute exists in a class, I can use tab completion for everything, avoid
> type-o's, etc. So I was recently thrilled to discover type hinting in
> python, and support included in pycharm. I'm coming back to python now (for
> the last few months).
>
>
>
> In python 3.6.1, and pycharm CE 2017.1.1 on windows (I haven't tested
> other versions or other platforms):
>
>
>
> The following is recognized and supported by pycharm, but then at runtime,
> python throws an exception:
>
>
>
> #!/usr/bin/env python3
>
>
>
> def foo(bars: list[str]):
>
> for bar in bars:
>
> if bar.startswith("hi"):
>
> raise
> ValueError("bar should never say hi")
>
> return True
>
>
>
>
>
> if foo(["a","b","c"]):
>
> print("Ok")
>
>
>
>
>
> TypeError: 'type' object is not subscriptable
>
>
>
> The problem is that python doesn't recognize list[str] as a type. Pycharm
> handles it, and everything works fine if I'm using a non-subscripted type,
> like plain old int, or str, or anything else.
>
>
>
> Is this a bug, or is it something python simply hasn't implemented yet, or
> is it something that's not going to be implemented?
>
>
>
> Is there a workaround?
>
> ___
> Python-Dev mailing list
> Python-Dev@python.org
> https://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe: https://mail.python.org/mailman/options/python-dev/
> levkivskyi%40gmail.com
>
>
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Re: [Python-Dev] Type hinting: TypeError: 'type' object is not subscriptable
> From: Ivan Levkivskyi [mailto:levkivs...@gmail.com] > > You should use List[int] (note capital first letter) and similar for other > generic > types. > Please read https://docs.python.org/3/library/typing.html > The fact that this is accepted by PyCharm is a PyCharm bug, and should be > reported on their tracker. Thank you. I've reported the issue to jetbrains, and also reported the jetbrains help page for type hinting in pycharm, which describes and provides examples using lowercase, and is where I learned about python type hinting. Based on what you've said, it appears it's both a pycharm bug, and also a jetbrains documentation bug. ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
