Sometimes you need a file-like object when all you have is an iterator, for instance when using psycopg2's cursor.copy_from. This class will handle the impedance mismatch.

iter_file.py

import io
import sys

class IteratorFile(io.TextIOBase):
    """ given an iterator which yields strings,
    return a file like object for reading those strings """

    def __init__(self, it):
        self._it = it
        self._f = io.StringIO()

    def read(self, length=sys.maxsize):

        try:
            while self._f.tell() < length:
                self._f.write(next(self._it) + "\n")
                
        except StopIteration as e:
            # soak up StopIteration. this block is not necessary because
            # of finally, but just to be explicit
            pass

        except Exception as e:
            print("uncaught exception: {}".format(e))
            
        finally:
            self._f.seek(0)
            data = self._f.read(length)

            # save the remainder for next read
            remainder = self._f.read()
            self._f.seek(0)
            self._f.truncate(0)
            self._f.write(remainder)
            return data

    def readline(self):
        return next(self._it)

Thanks for asking!