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tarfile.open(): Protocols for pipe modes #12182

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srittau opened this issue Jun 21, 2024 · 0 comments
Open

tarfile.open(): Protocols for pipe modes #12182

srittau opened this issue Jun 21, 2024 · 0 comments

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@srittau
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srittau commented Jun 21, 2024 •
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The pipe modes for tarfile.open() require only a simplified file object, not the full protocol. From the documentation:

For special purposes, there is a second format for mode: 'filemode|[compression]'. tarfile.open() will return a TarFile object that processes its data as a stream of blocks. No random seeking will be done on the file. If given, fileobj may be any object that has a read() or write() method (depending on the mode) that works with bytes. [...]

But currently, adding support for those modes is not possible, since mypy can't process string literals that contain a pipe character: python/mypy#16367. This will be fixed in mypy 1.11.
@AlexWaygood AlexWaygood mentioned this issue Jun 21, 2024
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tsibley added a commit to nextstrain/cli that referenced this issue Sep 5, 2024
@tsibley
runner.conda: Ignore newly failing type check for tarfile.open()
c79a8f3 
This started failing recently with newer typeshed stubs for
tarfile.open() (and/or newer stubs for requests.Response?).

mypy fails with:

    nextstrain/cli/runner/conda.py:220: error: Argument "fileobj" to "open" has incompatible type "Union[HTTPResponse, Any]"; expected "Optional[IO[bytes]]"

and pyright with:

    nextstrain/cli/runner/conda.py:220:14 - error: No overloads for "open" match the provided arguments (reportCallIssue)
    nextstrain/cli/runner/conda.py:220:58 - error: Argument of type "Literal['r|*']" cannot be assigned to parameter "mode" of type "_FileCreationModes" in function "open"
      Type "Literal['r|*']" is not assignable to type "_FileCreationModes"
        "Literal['r|*']" is not assignable to type "Literal['a']"
        "Literal['r|*']" is not assignable to type "Literal['w']"
        "Literal['r|*']" is not assignable to type "Literal['x']" (reportArgumentType)

I'm guessing the difference is because they match the different
overloads of tarfile.open().

I dug into it a little¹, but the stubs here seem a bit scattershot at
the moment so I stopped and went with an ignore.  An alternative fix is
casting response.raw to BinaryIO, but that seemed uglier and worse than
an ignore.

¹ See <python/typeshed#12117> (implicated)
  and <python/typeshed#12181> (open, may fix?)
  and <python/typeshed#12182> (open, may fix?)
tsibley added a commit to nextstrain/cli that referenced this issue Sep 5, 2024
@tsibley
runner.conda: Ignore newly failing type check for tarfile.open()
73ed6cb 
This started failing recently with newer typeshed stubs for
tarfile.open() (and/or newer stubs for requests.Response?).

mypy fails with:

    nextstrain/cli/runner/conda.py:220: error: Argument "fileobj" to "open" has incompatible type "Union[HTTPResponse, Any]"; expected "Optional[IO[bytes]]"

and pyright with:

    nextstrain/cli/runner/conda.py:220:14 - error: No overloads for "open" match the provided arguments (reportCallIssue)
    nextstrain/cli/runner/conda.py:220:58 - error: Argument of type "Literal['r|*']" cannot be assigned to parameter "mode" of type "_FileCreationModes" in function "open"
      Type "Literal['r|*']" is not assignable to type "_FileCreationModes"
        "Literal['r|*']" is not assignable to type "Literal['a']"
        "Literal['r|*']" is not assignable to type "Literal['w']"
        "Literal['r|*']" is not assignable to type "Literal['x']" (reportArgumentType)

I'm guessing the difference is because they match the different
overloads of tarfile.open().

I dug into it a little¹, but the stubs here seem a bit scattershot at
the moment so I stopped and went with an ignore.  An alternative fix is
casting response.raw to BinaryIO, but that seemed uglier and worse than
an ignore.

¹ See <python/typeshed#12117> (implicated)
  and <python/typeshed#12181> (open, may fix?)
  and <python/typeshed#12182> (open, may fix?)
@tsibley tsibley mentioned this issue Sep 5, 2024
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@srittau