base: Replace __file__ with pkgutil

`__file__` is an optional attribute which isnt available in zipapps
and PyOxidizer.  Use pkgutil.get_data instead.

Closes pypi#25

Author: jayvdb

stdlib_list/__init__.py

@@ -1,6 +1,13 @@
 from ._version import get_versions
+
 __version__ = get_versions()['version']
 del get_versions
 
 # Import all the things that used to be in here for backwards-compatibility reasons
-from .base import stdlib_list, in_stdlib, get_canonical_version, short_versions, long_versions, base_dir, list_dir
+from .base import (
+    stdlib_list,
+    in_stdlib,
+    get_canonical_version,
+    short_versions,
+    long_versions,
+)

stdlib_list/base.py

@@ -1,17 +1,14 @@
 from __future__ import print_function, absolute_import
 
 import os
+import pkgutil
 import sys
 
 try:
     from functools import lru_cache
 except ImportError:
     from functools32 import lru_cache
 
-base_dir = os.path.dirname(os.path.realpath(__file__))
-
-list_dir = os.path.join(base_dir, "lists")
-
 long_versions = ["2.6.9", "2.7.9", "3.2.6", "3.3.6", "3.4.3", "3.5", "3.6",
                  "3.7", "3.8"]
 
@@ -45,10 +42,11 @@ def stdlib_list(version=None):
     version = get_canonical_version(version) if version is not None else '.'.join(
         str(x) for x in sys.version_info[:2])
 
-    module_list_file = os.path.join(list_dir, "{}.txt".format(version))
+    module_list_file = os.path.join("lists", "{}.txt".format(version))
+
+    data = pkgutil.get_data("stdlib_list", module_list_file).decode()
 
-    with open(module_list_file) as f:
-        result = [y for y in [x.strip() for x in f.readlines()] if y]
+    result = [y for y in [x.strip() for x in data.splitlines()] if y]
 
     return result