Replace `imp` with `importlib` is available

2 files changed, 33 insertions, 19 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 8942df65..90454a5d 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -2,9 +2,11 @@
 Revision 4.4.10, released 2019-04-XX
 ------------------------------------
 
-- Fix to respect non-default timer resolution in asyncore main loop
-- Fix to update call interval of the existing periodic dispatcher jobs
-  on interval change (via .setTimerResolution())
+- Rebased MIB importing code onto `importlib` because `imp` is long
+  deprecated
+- Fixed asyncore main loop to respect non-default timer resolution
+- Fixed `.setTimerResolution()` behaviour of abstract main loop dispatcher
+  to update call intervals of the existing periodic dispatcher jobs
 
 Revision 4.4.9, released 2019-02-09
 -----------------------------------
diff --git a/pysnmp/smi/builder.py b/pysnmp/smi/builder.py
index 87c6b683..2f55b8eb 100644
--- a/pysnmp/smi/builder.py
+++ b/pysnmp/smi/builder.py
@@ -6,16 +6,32 @@
 #
 import os
 import sys
-import imp
 import struct
 import marshal
 import time
 import traceback
 
 try:
+    import importlib
+
+    PY_MAGIC_NUMBER = importlib.util.MAGIC_NUMBER
+    SOURCE_SUFFIXES = importlib.machinery.SOURCE_SUFFIXES
+    BYTECODE_SUFFIXES = importlib.machinery.BYTECODE_SUFFIXES
+
+except ImportError:
+    import imp
+
+    PY_MAGIC_NUMBER = imp.get_magic()
+    SOURCE_SUFFIXES = [imp.PY_SOURCE]
+    BYTECODE_SUFFIXES = [imp.PY_COMPILED]
+
+PY_SUFFIXES = SOURCE_SUFFIXES + BYTECODE_SUFFIXES
+
+try:
     from errno import ENOENT
 except ImportError:
     ENOENT = -1
+
 from pysnmp import version as pysnmp_version
 from pysnmp.smi import error
 from pysnmp import debug
@@ -31,13 +47,7 @@ else:
 class __AbstractMibSource(object):
     def __init__(self, srcName):
         self._srcName = srcName
-        self.__magic = imp.get_magic()
-        self.__sfx = {}
         self.__inited = None
-        for sfx, mode, typ in imp.get_suffixes():
-            if typ not in self.__sfx:
-                self.__sfx[typ] = []
-            self.__sfx[typ].append((sfx, len(sfx), mode))
         debug.logger & debug.flagBld and debug.logger('trying %s' % self)
 
     def __repr__(self):
@@ -45,13 +55,13 @@ class __AbstractMibSource(object):
 
     def _uniqNames(self, files):
         u = set()
+
         for f in files:
             if f.startswith('__init__.'):
                 continue
-            for typ in (imp.PY_SOURCE, imp.PY_COMPILED):
-                for sfx, sfxLen, mode in self.__sfx[typ]:
-                    if f[-sfxLen:] == sfx:
-                        u.add(f[:-sfxLen])
+
+            u.update(f[:-len(sfx)] for sfx in PY_SUFFIXES if f.endswith(sfx))
+
         return tuple(u)
 
     # MibSource API follows
@@ -76,9 +86,10 @@ class __AbstractMibSource(object):
     def read(self, f):
         pycTime = pyTime = -1
 
-        for pycSfx, pycSfxLen, pycMode in self.__sfx[imp.PY_COMPILED]:
+        for pycSfx in BYTECODE_SUFFIXES:
+
             try:
-                pycData, pycPath = self._getData(f + pycSfx, pycMode)
+                pycData, pycPath = self._getData(f + pycSfx, 'rb')
 
             except IOError:
                 why = sys.exc_info()[1]
@@ -91,7 +102,7 @@ class __AbstractMibSource(object):
                     raise error.MibLoadError('MIB file %s access error: %s' % (f + pycSfx, why))
 
             else:
-                if self.__magic == pycData[:4]:
+                if PY_MAGIC_NUMBER == pycData[:4]:
                     pycData = pycData[4:]
                     pycTime = struct.unpack('<L', pycData[:4])[0]
                     pycData = pycData[4:]
@@ -103,7 +114,8 @@ class __AbstractMibSource(object):
                 else:
                     debug.logger & debug.flagBld and debug.logger('bad magic in %s' % pycPath)
 
-        for pySfx, pySfxLen, pyMode in self.__sfx[imp.PY_SOURCE]:
+        for pySfx in SOURCE_SUFFIXES:
+
             try:
                 pyTime = self._getTimestamp(f + pySfx)
 
@@ -125,7 +137,7 @@ class __AbstractMibSource(object):
             return marshal.loads(pycData), pycSfx
 
         if pyTime != -1:
-            modData, pyPath = self._getData(f + pySfx, pyMode)
+            modData, pyPath = self._getData(f + pySfx, 'r')
             return compile(modData, pyPath, 'exec'), pyPath
 
         raise IOError(ENOENT, 'No suitable module found', f)