--Have you been out for lunch? she asked. I was going to leave immediately.
Now, with a first-person narrator, this leaves open the following possibilities:
"Have you been to lunch?" she asked. "I was going to leave immediately."
"Have you been to lunch?" she asked. I was going to leave immediately.
Sometimes Jensen appears to be introducing a consistency, where all stretches of dialog begin with --. But sometimes not, and consistency doesn't mean "sometimes." Grrrarrr.
I understand that there are times when obfuscation lends depth to the text and variety of meanings and blah blah etc. But I will submit that who is going to leave immediately to get their lunch is not one of those times. No. Obfuscation on the lunch question is a boring annoyance, not a bit of fascinating depth and insight into the human condition.
We have dialog punctuation conventions for a reason. If you choose not to use them, I would like to see a very, very, very good reason why not. And "I thought it looked arty on the page" is not a very, very, very good reason. It's not even a mediocre reason, actually. Why not mark the end of a bit of dialog? Tell me: why not? Why not consistently mark the beginning?
Quotation marks. I don't care if they're single or double. They are your friends. Use them. If you don't know how, that is your zeroth task in writing a novel, before a plot outline or a character sketch or an organic flowing beginning or whatever it is that floats your very own little fruitbat writer boat. Quotation marks. I really mean it. I will put up with this behavior in some writers who are otherwise very good*, but I won't like it in them, either. I'll praise their book and then complain about the stupid dialog conventions.
Yes, I realize that I am a mean, horrible, cranky, rigid person. Deal.
*If porphyrin had not recommended this book, I'd have quit on page 2, when the title character starts talking to someone else and using the damned dash.