swig/Examples/python/import_packages/from_init1
William S Fulton ff93f2e26e Skip Python subprocess calls in import_packages testcase on Windows
Getting these kind of errors on Appveyor which uses mingw/cygwin to run
a Python interpreter:

Native windows Python 3.6 running under cygwin and mingw Python 3.7 running under mingw:
  Fatal Python error: _Py_HashRandomization_Init: failed to get random
  numbers to initialize Python

Cygwin Python 2.7 running under cygwin:
  0 [main] python2.7 496 child_info_fork::abort: address space needed by '_foo.dll' (0x6D0000)
  is already occupied
2018-12-06 06:50:57 +00:00
..
py2 Remove use of preinst-swig script 2015-08-21 22:43:17 +01:00
py3 Remove use of preinst-swig script 2015-08-21 22:43:17 +01:00
Makefile Remove realpath from python/import_packages example 2015-08-20 06:19:12 +01:00
README Fixed SF bug #1297 (Python imports) 2013-12-24 17:22:25 +00:00
runme.py Skip Python subprocess calls in import_packages testcase on Windows 2018-12-06 06:50:57 +00:00

This example tests the %import directive and python import from __init__.py.

This case is not correctly handled by swig 2.

The issue was reported as Source Forge bug #1297 and later as GitHub issue #7.

Use 'python runme.py' to run a test.


Overview:
---------

The example defines 2 different extension modules--each wrapping a separate C++
class.

     pyX/pkg2/foo.i        - Pkg2_Foo class
     pyX/pkg2/bar.i        - Pkg2_Bar class derived from Pkg2_Foo

and the package pyX.pkg2 has:

     pyX/pkg2/__init__.py  - which imports something from "bar" module (we
                              import Pkg2_Bar class, but it is not the clue,
                              the clue is the 'from' keyword)

For example with python2.x the py2/pkg2/__init__.py imports Pkg2_Bar class
as follows

    from bar import Pkg2_Bar                    # [1]

Such cases doesn't work when fully qualified python module names are used by
swig (swig 2.0.10, e.g.) to generate python import directives (SF bug #1297).
The generated file "py2/pkg2/bar.py" has following lines:

    import py2.pkg2.foo                        # [2]
    class Pkg2_Bar(py2.pkg2.foo.Pkg2_Foo):     # [3]

but it's not possible to import anything from py2.pkg2 subpackage, e.g.

    import py2.pkg2

fails with the following exception:

Traceback (most recent call last):
  File "runme.py", line 3, in <module>
      import py2.pkg2
  File "py2/pkg2/__init__.py", line 7, in <module>
      from .bar import Pkg2_Bar
  File "py2/pkg2/bar.py", line 71, in <module>
      class Pkg2_Bar(py2.pkg2.foo.Pkg2_Foo):
  AttributeError: 'module' object has no attribute 'pkg2'


It seems like during the import [1], the sub-package pkg2 is not yet fully
initialized, so py2.pkg2 is not known. The above exception is raised at
line [3]. The problem disappears, for example, if we force swig to use relative
package names.

If everything works well, the package py2.pkg2 shall load properly.

Unix:
-----
- Run make
- Run the test as described above