From: John Cowan <xxxxxx@ccil.org>

Date: Tue, Sep 3, 2019 at 5:56 PM

So here's the generator:

(define make-directory-files-generator

(case-lambda

((dir dot-files?) (make-directory-files-generator* dir dot-files?))

((dir) (make-directory-files-generator* dir #f))))

(define (make-directory-files-generator* dir dot-files?)

(let ((dir-obj (open-directory dir dot-files?))

(eof (eof-object)))

(lambda ()

(let ((f (read-directory dir-obj)))

(if (eq? f eof) (close-directory dir-obj))

f))))

I haven't actually tested this, but it's at least conceptually correct.

It works through the close-directory operation, after which it continues to attempt to read the closed dir-obj, raising a low-level POSIX exception. On reading the generator SRFI 158, I note:

After a finite generator has generated all its values, it will return an end-of-file object for all subsequent calls.

How important is it to remedy this?

[ We're going to keep the "mostly harmless" directory-files. In prior discussions we liked directory-fold, but decided not to expose it. ]