(import (only ...)) strange behaviour

[Caolan McMahon]

I noticed that I had to manually (use posix) before loading the LMDB module. But the module already does: (import (only posix create-directory delete-directory))

That has led to the following test cases:

;; create-directory not defined
(import (only posix create-directory))
(print create-directory)
(print delete-directory)

;; delete-directory is imported when it shouldn't be
(use (only posix create-directory))
(print create-directory)
(print delete-directory)

And this shows how I manually (use posix) beforehand to get around this issue:

;; module A (a.scm)
(module a *
  (import chicken scheme)
  (import (only posix create-directory))
  (print create-directory)
  (print delete-directory))

(use posix)
(load "a.scm")
(import a)

This now correctly imports _only_ the create-directory procedure. If I remove the (use posix) line, it will fail as in the first example. I can also replace (use posix) with (require-library posix) and it will work.

These examples were just run in csi - however I originally found it by using the system's installed lmdb module inside my own module compiled via csc.

[sjamaan]

You need use rather than import. import doesn't load code, it only loads the so-called "import library" which registers which identifiers are exported by the module.

This is a bit of a FAQ/pitfall/caveat in CHICKEN 4. In CHICKEN 5, we've made use and import behave identically because it is rarely actually useful to only load the import library but not the code.