Dylink doesn't allow us to call functions that start with '_'

[aaaaalbert]

Note: This was SeattleTestbed/repy_v2#60 previously. I'm just attaching it to the correct issue tracker, but have not reviewed it for aptness.

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If we import a file using dylink, it won't allow us to call functions that start with an underscore. This is different from how python import works. Not sure if this is an intended behaviour or not. Below is a piece of code that fails.

foo.py:

def _foo():
    print "foo"

bar.py:

from repyportability import *
add_dy_support(locals())

foo = dy_import_module("foo.py")

try:
  foo._foo()
except AttributeError, err:
  print "Unable to call foo._foo() when using dylink.\n" + str(err)

import foo
foo._foo()

If we run bar.py, we get the following error when calling foo._foo() (when using dylink):

monzum@TestUbuntu:$ python bar.py 
Unable to call foo._foo() when using dylink.
ImportedModule instance has no attribute '_foo'

However once we use 'import' to import it, we are able to call foo._foo().

[aaaaalbert]

Indeed, this issue (and also #153) shows that dylink (and also repyportability in combination with it, see SeattleTestbed/portability#28) doesn't quite work as Python's import / from MODULE import * do. I've created a few additional unit tests to demonstrate what should and what does happen, see aaaaalbert/seattlelib_v2@bb285e4. From the commit message:

The expected behavior is to

• do import module._underscorename, but
• don't add _underscorename via from module import *

However, the corresponding dy_import_module and dy_import_module_symbols get it both wrong.

[aaaaalbert]

See also here for Python's import behavior: https://docs.python.org/2/reference/simple_stmts.html#the-import-statement