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pythontyping

typing.Tuple from list of types

I have a list of type objects and want to construct a typing.Tuple object. Is there a way to do this?

tys = [int, str]    # This is known only at runtime
x = typing.Tuple(tys)   # TypeError: Type Tuple cannot be instantiated; use tuple() instead

Any help will be appreciated. Thanks.

Edit: For clarification about the question-

What I am trying to do - visit a Tuple in python AST and annotate its type. For this the list tys is made out of a loop (and so, I could not start with a tuple in the start). Now, I definitely have to annotate it with a typing.Tuple object and hence the question.

Solution

  • I got the solution.

    x = typing.Tuple[tuple(tys)] # This works

    Edit: This works for all typing constructs. For eg. while typing.Union(tys) and typing.Union[tys] will give an error, typing.Union[tuple(tys)] works. I am not sure if this is a general "python" thing, or it is special with the typing module. I will update this answer once I know that.