In modern versions of Python one can have static type analysis using function annotations, according to PEP 484. This is made easy through the typing module.
Now I’m wondering how I would give a “type hint” towards a “filestream”.
def myfunction(file: FILETYPE): pass with open(fname) as file: myfunction(file)
What would I insert as FILETYPE
?
Using print(type(file))
returns <class '_io.TextIOWrapper'>
which isn’t clear at all.
Isn’t there a generic “file” type?
Advertisement
Answer
You can use typing.IO
, typing.TextIO
, and typing.BinaryIO
to represent different types of I/O streams. To quote the documentation:
сlass typing.IO
class typing.TextIO
class typing.BinaryIOGeneric type
IO[AnyStr]
and its subclassesTextIO(IO[str])
andBinaryIO(IO[bytes])
represent the types of I/O streams such as returned byopen()
.