Python 3.5+typingterm

typing.TextIO

I/O streams

The type for text file streams in annotations.

Syntax

def f(stream: typing.TextIO) -> None: ...

This is an abstract stand-in type for annotations, not a class you instantiate (hence the example touches TextIO.__name__ rather than an instance). Annotate with it when your function accepts any text stream — a file from open() in text mode, io.StringIO, or sys.stdout — rather than one concrete file type.

Examples

from typing import IO, TextIO
import io
print(TextIO.__name__)   # → TextIO

from typing import IO, TextIO
import io
def read_all(f: TextIO) -> str: return f.read()
print(read_all(io.StringIO('hello')))   # → hello

from typing import IO, TextIO
import io
def first_word(f: TextIO) -> str: return f.read().split()[0]
print(first_word(io.StringIO('раз два три')))   # → раз
print(issubclass(TextIO, IO))   # → True
print(isinstance(io.StringIO(), TextIO))   # → False

See also

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