Contextmanager which opens the default editor on a given text and lets you edit it, then returns the result

editor.py

import os
import tempfile
from subprocess import call

EDITOR = os.environ.get('EDITOR', 'vi')


class Editor:

    def __init__(self, text):
        self.text = text
        # Set a default result
        self.result = text

    def open(self):
        with tempfile.NamedTemporaryFile(suffix='.tmp') as temp:
            temp.write(self.text.encode('utf-8'))
            temp.flush()
            call([EDITOR, temp.name])
            temp.seek(0)
            self.result = temp.read().decode('utf-8')

    @staticmethod
    def _is_comment(line):
        return line.startswith('#')

    @property
    def is_edited(self):
        return self.text != self.result

    @property
    def is_empty(self):
        # Filter out empty lines and comments (starting with #)
        return len(list(filter(lambda line: line and not line.startswith('#'), self.result.split('\n')))) == 0

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        pass