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List: python-ideas
Subject: [Python-ideas] Re: PEP 472 - regarding d[x=1, y=2] and similar
From: Todd <toddrjen () gmail ! com>
Date: 2020-08-20 18:58:28
Message-ID: CAFpSVp+qAxyPypvFp6XNYP0=2zVD_mpAKUz5vZ03HFB6csTkbQ () mail ! gmail ! com
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On Thu, Aug 20, 2020 at 2:28 PM Jonathan Fine <jfine2358@gmail.com> wrote:
> Hi Todd
>
> You wrote:
>
> I think this is a bad idea, since it would mean classes could seem to
>> support keyword arguments but silently do the completely wrong thing,
>> especially if someone accidentally uses an older version.
>>
>
> I don't see this happening, and certainly don't see it as a new problem.
> To help me understand, please provide an example where this happens.
>
> It would be best to wait a few days first, after I've fixed
> https://github.com/jfine2358/python-kwkey/issues/2
>
As I said, it could very easily happen in xarray. xarray has a structure
called a Dataset, which is a dict-style container for DataArrays (labelled
multidimensional arrays). It supports both selecting an array by key or
indexing all the arrays by their indices. So imagine a labelled array 'y'
with dimensions 'a' and 'b'. So consider this example:
ds = Dataset({'y': y})
ds[a=1, b=2] = y[a=2, b=3]
If xarray supports keyword arguments, this would assign to the
corresponding values. If it didn't, it would create a new element of the
Dataset containing "y[a=2, b=3]". But "y" would continue working as it
would, only with different values than expected.
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<div dir="ltr"><div dir="ltr">On Thu, Aug 20, 2020 at 2:28 PM Jonathan Fine <<a \
href="mailto:jfine2358@gmail.com">jfine2358@gmail.com</a>> wrote:<br></div><div \
class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px \
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Hi \
Todd</div><div><br></div><div>You wrote:</div><div><br></div><div \
class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px \
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div \
class="gmail_quote"><div>I think this is a bad idea, since it would mean classes \
could seem to support keyword arguments but silently do the completely wrong thing, \
especially if someone accidentally uses an older \
version.</div></div></div></blockquote><div><br></div><div>I don't see this \
happening, and certainly don't see it as a new problem. To help me understand, \
please provide an example where this happens.</div><div><br></div><div>It would be \
best to wait a few days first, after I've fixed</div><div><a \
href="https://github.com/jfine2358/python-kwkey/issues/2" \
target="_blank">https://github.com/jfine2358/python-kwkey/issues/2</a></div></div></div></blockquote><div><br></div><div>As \
I said, it could very easily happen in xarray. xarray has a structure called a \
Dataset, which is a dict-style container for DataArrays (labelled multidimensional \
arrays). It supports both selecting an array by key or indexing all the arrays by \
their indices. So imagine a labelled array 'y' with dimensions 'a' \
and 'b'. So consider this example:</div><div><br></div><div>ds = \
Dataset({'y': y})</div><div>ds[a=1, b=2] = y[a=2, \
b=3]</div><div><br></div><div>If xarray supports keyword arguments, this would assign \
to the corresponding values. If it didn't, it would create a new element of the \
Dataset containing "y[a=2, b=3]". But "y" would continue \
working as it would, only with different values than expected. </div></div></div>
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