Error finding package error when looking for for a python exception from imported module

[vijay edwin]

I am importing the below library

https://docs.python.org/3/library/ipaddress.html#custom-exceptions

like this

(py4cl:import-module "ipaddress" :as "ipaddress")

in an asdf project containing this function

(defun mask->cidr (mask)
  (let* ((ipv4-network (ipaddress:ip_network (concatenate 'string "0.0.0.0/" mask))))
    (py4cl:chain ipv4-network prefixlen)))

When loading my project in quicklisp I get the error

Error finding package for symbol "ADDRESSVALUEERROR":
 The name "IPADDRESS" does not designate any package.
   [Condition of type SB-KERNEL:SIMPLE-PACKAGE-ERROR]

where ADDRESSVALUEERROR is an python Exception for the this library apparently

https://docs.python.org/3/library/ipaddress.html#ipaddress.AddressValueError

Curious if

a) anyone can reproduce this
b) if there is a way to import using the from method, I think in python you would get access to AddressValueError like so

from ipaddress import AddressValueError

but not clear if that is possible in py4cl

thanks! great lib btw

[Shubhamkar Ayare]

With the following code inside the source code file accompanying the corresponding asd file, the asd-system is loaded into SLIME (for this as well as the forked version - with appropriate changes):

(eval-when (:compile-toplevel :load-toplevel :execute)
  (py4cl:import-module "ipaddress" :as "IPADDRESS" :reload t))

(defpackage py4cl-test
  (:use :py4cl :cl))
(in-package :py4cl-test)

(defun mask->cidr (mask)
  (let* ((ipv4-network (ipaddress:ip_network (concatenate 'string
                                                          "0.0.0.0/" mask))))
    (py4cl:chain ipv4-network prefixlen)))

I didn't encounter this issue while packaging this - or so I thought. However, as I tested it now, wrapping it inside (eval-when) is necessary.

Even, defpackage macroexpands to contain a (eval-when). I've added it in the forked version - but this should resolve your issue. Thank you for the feedback!

EDIT: Earlier, I had mentioned (eval-when (:compile-toplevel)) - however, that gives errors when the package is not required to be (re)compiled: since that code is run only during compilation time.

[Shubhamkar Ayare]

b) if there is a way to import using the from method, I think in python you would get access to AddressValueError like so

from ipaddress import AddressValueError

You can use the :from argument of import-function:

CL-USER> (import-function "AddressValueError" :from "ipaddress")
ADDRESSVALUEERROR

(Did you check (describe 'import-function)? Or did you mean something different?)

[Shubhamkar Ayare]

With the following code inside the source code file accompanying the corresponding asd file, the asd-system is loaded into SLIME (for this as well as the forked version - with appropriate changes):

(eval-when (:compile-toplevel :load-toplevel :execute)
  (py4cl:import-module "ipaddress" :as "IPADDRESS" :reload t))

(defpackage py4cl-test
  (:use :py4cl :cl))
(in-package :py4cl-test)

(defun mask->cidr (mask)
  (let* ((ipv4-network (ipaddress:ip_network (concatenate 'string
                                                          "0.0.0.0/" mask))))
    (py4cl:chain ipv4-network prefixlen)))

I didn't encounter this issue while packaging this - or so I thought. However, as I tested it now, wrapping it inside (eval-when) is necessary.

Even, defpackage macroexpands to contain a (eval-when). I've added it in the forked version - but this should resolve your issue. Thank you for the feedback!

EDIT: Earlier, I had mentioned (eval-when (:compile-toplevel)) - however, that gives errors when the package is not required to be (re)compiled: since that code is run only during compilation time.

A still better method is to use the :export option of defpackage - that should avoid having to do all the work at every execution time.

[Shubhamkar Ayare]

As far as I understand, 0821956 should have fixed this.