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Tony Hansen

Terry Schmalzried

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Comment: Reverted from v. 10

...

Your .py files will now have a series of blocks that look like this, using C preprocessor syntax:

NOTE: The sense of the "#ifdef/#ifndef" is backwards from what we really want,

but this will be dealt with in a later section below.

I've added annotated the lines further to make it clearer which lines are the python2 and which are the python3 code.

. . .

#ifndef USING_PYTHON2

from logginginterface import *                             # python2 code

#else /* USING_PYTHON2 */

from .logginginterface import *                            # python3 code

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

import urlliburllib                                              # python2 code

#else /* USING_PYTHON2 */

import urllib.request, urllib.parse, urllib.errorerror          # python3 code

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

  return urllib.quote(str(s), '')'')                          # python2 code

#else /* USING_PYTHON2 */

  return urllib.parse.quote(str(s), '')                    # python3 code

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

  os.umask(077)                                           # python2 code

#else /* USING_PYTHON2 */

  os.umask(0o77)                                          # python3 code

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

  if openstack.has_key('custom_configuration'):           # python2 code

#else /* USING_PYTHON2 */

  if 'custom_configuration' in openstack:                 # python3 code

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

  print >>fp, binascii.hexlify(b).decode('utf-8')')        # python2 code

#else /* USING_PYTHON2 */

  print(binascii.hexlify(b).decode('utf-8'), file=fp)    # python3 code

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

  debug("ctx node has the following Properties: {}".format(i.properties.keys()))

#else /* USING_PYTHON2 */

  debug("ctx node has the following Properties: {}".format(list(i.properties.keys())))

#endif /* USING_PYTHON2 */

. . .

#ifndef USING_PYTHON2

  for k, nv in want.items():                           # python2 code

#else /* USING_PYTHON2 */

  for k, nv in list(want.items()):                     # python3 code

#endif /* USING_PYTHON2 */

. . .

...

You need to change blocks such as this:

#ifndef USING_PYTHON2

some python2 code

#else /* USING_PYTHON2 */

some python3 code

#endif /* USING_PYTHON2 */


#ifdef USING_PYTHON2

   some python3 code

#endif /* USING_PYTHON2 */

to this. Make CERTAIN that the indentation is adjusted as well.

if USING_PYTHON2:

  some python2 code

else:

  some python3 code


if not USING_PYTHON2:

  some python3 code

Yes, there is some cognitive dissonance for changing "#ifndef" to "if", but the rest of the generated code is set up properly to be able to quickly edit the code.

  • Search for all instances of "#ifndef USING_PYTHON2" and change "#ifndef" to "if" and add a trailing ":".
  • Search for all instances of "#else /* USING_PYTHON2 */" and change that to "else:".
  • Remove all instances of "#endif /* USING_PYTHON2 */" from the code.
  • Re-indent the lines in between.


  • You should also search for "#ifdef USING_PYTHON2" and change that to "if not USING_PYTHON2:".

Import Statements

The way that imports of functions found in local files changes in Python3. So change blocks such as this:

#ifndef USING_PYTHON2

from logginginterface import *     # python2 code

#else /* USING_PYTHON2 */

from .logginginterface import *    # python3 code

#endif /* USING_PYTHON2 */

...

#ifndef USING_PYTHON2

import urlliburllib     # python2 code

#else /* USING_PYTHON2 */

import urllib.request, urllib.parse, urllib.errorerror     # python3 code

#endif /* USING_PYTHON2 */

...

if USING_PYTHON2:

  from logginginterface import *     # python2 code

  import urllib

else:

  from .logginginterface import *import *     # python3 code

  import urllib.request, urllib.parse, urllib.error

...

#ifndef USING_PYTHON2

  return urllib.quote(str(s), '')           # python2 code

#else /* USING_PYTHON2 */

  return urllib.parse.quote(str(s), '')     # python3 code

#endif /* USING_PYTHON2 */

...

#ifndef USING_PYTHON2

  os.umask(077)     # python2 code

#else /* USING_PYTHON2 */

  os.umask(0o77)     # python3 code

#endif /* USING_PYTHON2 */

...

#ifndef USING_PYTHON2

  if openstack.has_key('custom_configuration'):     # python2 code

#else /* USING_PYTHON2 */

  if 'custom_configuration' in openstack:     # python3 code

#endif /* USING_PYTHON2 */

...

#ifndef USING_PYTHON2

  print >>fp, binascii.hexlify(b).decode('utf-8')     # python2 code

#else /* USING_PYTHON2 */

  print(binascii.hexlify(b).decode('utf-8'), file=fp)     # python3 code

#endif /* USING_PYTHON2 */

...

#ifndef USING_PYTHON2

  debug("ctx node has the following Properties: {}".format(i.properties.keys()))     # python2 code

#else /* USING_PYTHON2 */

  debug("ctx node has the following Properties: {}".format(list(i.properties.keys())))     # python3 code

#endif /* USING_PYTHON2 */

...