[4c2383f5c88e911]

  a = "test"
  if a < 1:
      print(a)

[tyingq]

There are some corner cases that run fine in python but trip up 2to3 tools, including this web based one. This code for example:

  print(set(x for x in range(2),))

[eesmith]

"asdf".encode("hex")

Is there a tool which knows to translate this to:

  import binascii
  binascii.b2a_hex(b"asdf")

Even worse, if the string isn't known to be a byte string or ASCII unicode string, it's something like:

  import binascii
  binascii.b2a_hex(s.encode("ascii") if isinstance(s, str) else s)

[tyingq]

Sure...that's a different thing though. Python 3's choice to introduce new types and change behavior of existing types means no automated tool can really decide what to do.

The snippet I posted is a little different in that it runs on both Python 2 as well as 3, but the 2to3 tools choke on it.

[eesmith]

Ahh, yes, you're right.

I'm still irritated by this specific case because my code and documentation used s.encode("hex") often, and it took a while to fix them all. Especially as the original code used both str and unicode hex-encoded values, so I couldn't drop in binascii. I ended up adding a C extension function.

[eesmith]

What is a 2to3 tool supposed to do here?

python2 prints "set([0, 1])" while python3 prints "{0,1}".

Is it supposed to normalize the str() so it matches Python2?

For that matter, the str() for floats has changed:

  % python
  Python 2.7.10 (default, Jul 30 2016, 19:40:32)
  [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> print(-1.0000000000000002)
  -1.0
  >>>
  % python3
  Python 3.6.0 (v3.6.0:41df79263a11, Dec 22 2016, 17:23:13)
  [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> print(-1.0000000000000002)
  -1.0000000000000002

[anc84]

What about it?

[4c2383f5c88e911]

"test" < 1 is a TypeError in python3, and it works in python2 (returns False), it is part of the pitfalls of porting code to python 3.

[PerryCox]

If you enter the code above into the website it responds with:

maybe the code is wrong?

[anc84]

It does not do that for me, the Python 3 version appears with no changes.