IronLanguages / IronLanguages/ironpython3

Dict unpacking fails with .NET Dictionary

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.NET interop
Dominant language
C#
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Forks
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Avg merge
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Merged PRs (30d)
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Description

The following should probably succeed:

def test(**d): print(d)

import System.Collections.Generic
d = System.Collections.Generic.Dictionary[str, int]()
d.Add("b", 2)
test(**{"a": 1}, **d)

but fails with

TypeError: 'Dictionary[str, int]' object is not a mapping

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the Python reproducer from the issue with IronPython and System.Collections.Generic.Dictionary[str, int]. Trace the handling of ** unpacking and the mapping check for the .NET Dictionary. Done means the example succeeds and produces the expected keyword arguments without the TypeError.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp, python
Domain
backend, compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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