How to ignore mypy errors when using NamedTuples with default values









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I have been able to have mypy do a type check on NamedTuple and use default values for NamedTuple.



However, I always have an error raised by mypy when I use default value.



Here is my code (I use Python 3.6)



class TestResult(NamedTuple):
"""To store results of a given Test Case"""

outcome: str
duration: Optional[int] # in seconds
comment: Optional[str]
msg: Optional[str]


TestResult.__new__.__defaults__ = (None,) * 3 # type: ignore # Hack for Python < 3.7


When I do passed_tc = TestResult("Passed"), I have the following error message




error:Too few arguments for "TestResult"




Anyone got an idea on how to tell mypy we can have optional arguments and avoid this error?










share|improve this question

























    up vote
    0
    down vote

    favorite












    I have been able to have mypy do a type check on NamedTuple and use default values for NamedTuple.



    However, I always have an error raised by mypy when I use default value.



    Here is my code (I use Python 3.6)



    class TestResult(NamedTuple):
    """To store results of a given Test Case"""

    outcome: str
    duration: Optional[int] # in seconds
    comment: Optional[str]
    msg: Optional[str]


    TestResult.__new__.__defaults__ = (None,) * 3 # type: ignore # Hack for Python < 3.7


    When I do passed_tc = TestResult("Passed"), I have the following error message




    error:Too few arguments for "TestResult"




    Anyone got an idea on how to tell mypy we can have optional arguments and avoid this error?










    share|improve this question























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I have been able to have mypy do a type check on NamedTuple and use default values for NamedTuple.



      However, I always have an error raised by mypy when I use default value.



      Here is my code (I use Python 3.6)



      class TestResult(NamedTuple):
      """To store results of a given Test Case"""

      outcome: str
      duration: Optional[int] # in seconds
      comment: Optional[str]
      msg: Optional[str]


      TestResult.__new__.__defaults__ = (None,) * 3 # type: ignore # Hack for Python < 3.7


      When I do passed_tc = TestResult("Passed"), I have the following error message




      error:Too few arguments for "TestResult"




      Anyone got an idea on how to tell mypy we can have optional arguments and avoid this error?










      share|improve this question













      I have been able to have mypy do a type check on NamedTuple and use default values for NamedTuple.



      However, I always have an error raised by mypy when I use default value.



      Here is my code (I use Python 3.6)



      class TestResult(NamedTuple):
      """To store results of a given Test Case"""

      outcome: str
      duration: Optional[int] # in seconds
      comment: Optional[str]
      msg: Optional[str]


      TestResult.__new__.__defaults__ = (None,) * 3 # type: ignore # Hack for Python < 3.7


      When I do passed_tc = TestResult("Passed"), I have the following error message




      error:Too few arguments for "TestResult"




      Anyone got an idea on how to tell mypy we can have optional arguments and avoid this error?







      python python-3.x namedtuple mypy






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 11 at 1:39









      Jean-Francois T.

      4,92712754




      4,92712754






















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          1
          down vote



          accepted










          Assign the values that need default values with the desired default values. For example:



          from typing import NamedTuple, Optional

          class Test(NamedTuple):
          foo: str
          bar: Optional[str] = None
          qux: int = 100

          t = Test("foo")


          I've tested that this works at runtime for both Python 3.6 and 3.7, and confirmed it type-checks as expected using mypy 0.641.






          share|improve this answer




















          • Nice, it's usually the simplest thing that you never think of.
            – Jean-Francois T.
            Nov 13 at 8:04










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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          1
          down vote



          accepted










          Assign the values that need default values with the desired default values. For example:



          from typing import NamedTuple, Optional

          class Test(NamedTuple):
          foo: str
          bar: Optional[str] = None
          qux: int = 100

          t = Test("foo")


          I've tested that this works at runtime for both Python 3.6 and 3.7, and confirmed it type-checks as expected using mypy 0.641.






          share|improve this answer




















          • Nice, it's usually the simplest thing that you never think of.
            – Jean-Francois T.
            Nov 13 at 8:04














          up vote
          1
          down vote



          accepted










          Assign the values that need default values with the desired default values. For example:



          from typing import NamedTuple, Optional

          class Test(NamedTuple):
          foo: str
          bar: Optional[str] = None
          qux: int = 100

          t = Test("foo")


          I've tested that this works at runtime for both Python 3.6 and 3.7, and confirmed it type-checks as expected using mypy 0.641.






          share|improve this answer




















          • Nice, it's usually the simplest thing that you never think of.
            – Jean-Francois T.
            Nov 13 at 8:04












          up vote
          1
          down vote



          accepted







          up vote
          1
          down vote



          accepted






          Assign the values that need default values with the desired default values. For example:



          from typing import NamedTuple, Optional

          class Test(NamedTuple):
          foo: str
          bar: Optional[str] = None
          qux: int = 100

          t = Test("foo")


          I've tested that this works at runtime for both Python 3.6 and 3.7, and confirmed it type-checks as expected using mypy 0.641.






          share|improve this answer












          Assign the values that need default values with the desired default values. For example:



          from typing import NamedTuple, Optional

          class Test(NamedTuple):
          foo: str
          bar: Optional[str] = None
          qux: int = 100

          t = Test("foo")


          I've tested that this works at runtime for both Python 3.6 and 3.7, and confirmed it type-checks as expected using mypy 0.641.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 12 at 2:45









          Michael0x2a

          22k1672125




          22k1672125











          • Nice, it's usually the simplest thing that you never think of.
            – Jean-Francois T.
            Nov 13 at 8:04
















          • Nice, it's usually the simplest thing that you never think of.
            – Jean-Francois T.
            Nov 13 at 8:04















          Nice, it's usually the simplest thing that you never think of.
          – Jean-Francois T.
          Nov 13 at 8:04




          Nice, it's usually the simplest thing that you never think of.
          – Jean-Francois T.
          Nov 13 at 8:04

















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