Python3 compatibility breaks brew file init command

[zebernst]

When executing the brew file init command (using Python 3.5.2), the following error is thrown:

Traceback (most recent call last):
  File "/usr/local/bin/brew-file", line 3162, in <module>
    main()
  File "/usr/local/bin/brew-file", line 3159, in main
    b.execute()
  File "/usr/local/bin/brew-file", line 2786, in execute
    self.initialize()
  File "/usr/local/bin/brew-file", line 1790, in initialize
    ans = self.ask_yn("Do you want to overwrite it?")
  File "/usr/local/bin/brew-file", line 880, in ask_yn
    yn = my_input(question + " [y/n]: ").lower()
  File "/usr/local/bin/brew-file", line 66, in my_input
    return input(word)
UnboundLocalError: local variable 'input' referenced before assignment

I believe that I fixed the issue on my installation by modifying the my_input function, and then making a similar revision to the my_decode function because it looked like it might cause similar errors in the future. These are my modifications:

from builtins import str, input

def my_decode(word):  # pragma: no cover
    """Decode when python3 is used."""

    return str(word.decode())

def my_input(word):  # pragma: no cover
    """Input method compatibility."""

    return input(word)

Now, type(my_decode(word)) returns <class 'str'> in Python 3 and <class 'future.types.newstr.newstr'> in Python 2. According to python-future,

"future contains a newstr type that is a backport of the str object from Python 3. This inherits from the Python 2 unicode class but has customizations to improve compatibility with Python 3’s str object."

Additionally, the input() method is now equivalent to raw_input() in Python 2, while remaining unchanged in Python 3. I didn't see any Python 2 input() calls that needed to be changed to eval(input()), but I could have missed one.

I don't know if you had your own reasons for not importing from the builtins module that come with the future module, and granted I did no testing other than looking to see if the brew file init command worked, but it seems to be working so far.

[rcmdnk]

Thank you for the feedback.

First of all, could you please upgrade brerw-file? It seems older version.
Current version is:

$ brew file --version
brew-file v4.1.3 15/Nov/2016

input function is built-in and I'm not sure why it shows before assignment error.
(could be something wrong in the old code, so it could be helpful if you could tell current version.)

About builtin module, future package is needed to be installed for python2,
so that these functions were implemented.

[zebernst]

Hey, I'm sorry I totally forgot about this thread. It's been pretty hectic with the end of the semester and all. I am, in fact, on the latest version of brew-file.

$ brew file --version
brew-file v4.1.3 15/Nov/2016

[rcmdnk]

Could you please check followings?

$ which python
$ type python
$ python --version
$ echo $PYTHONPATH

And test input w/o import, like:

$ python
Python 3.5.2 (default, Oct 12 2016, 06:30:24)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.38)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> input("test: ")
test: aaa
'aaa'
>>>

[zebernst]

I use pyenv to manage my Python installations and virtual environments, so I doubt that these will be very helpful to you (especially the blank $PYTHONPATH:

% which python
/usr/local/var/pyenv/shims/python
% pyenv which python
/usr/local/var/pyenv/versions/3.5.2/bin/python
% type python
python is /usr/local/var/pyenv/shims/python
% python --version
Python 3.5.2
% echo $PYTHONPATH    

Here's the test of input() in the python cli:

% python
Python 3.5.2 (default, Nov 28 2016, 12:44:30)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> input('test: ')
test: aaa

[rcmdnk]

brew-file uses shebang of #!/usr/bin/env python, so it is same python you are using.
And you can use input directly, so I don't know why you got an error of input...

Here is the minimum script of my_input:

#!/usr/bin/env python
is_python3 = -1


def my_input(word):
    """Input method compatibility."""

    global is_python3
    if is_python3 == -1:
        try:
            input = raw_input
            is_python3 = 0
        except:
            is_python3 = 1
    elif is_python3 == 0:
        input = raw_input
    return input(word)

print my_input("test: ")

Could you please try to run this script?

[rcmdnk]

if you still have a problem, re-open the issue.

[zebernst]

The problem had stopped occurring, but it just happened again today. I ran the script you gave (and changed the print statement on the last line to be correct for python 3) and got the following:

Traceback (most recent call last):
  File "/Users/zach/Downloads/inputtest.py", line 21, in <module>
    print(my_input("test: "))
  File "/Users/zach/Downloads/inputtest.py", line 19, in my_input
    return input(word)
UnboundLocalError: local variable 'input' referenced before assignment

I also added a statement to the script to test which version of python is running (print(sys.version)) and I verified that the script is being run with Python 3.5.2.

[rcmdnk]

Now I understand the problem.
It is actually problematic code, sorry.

fixed input problem at python3 · rcmdnk/homebrew-file@cbbbc70

This fix should solve it, in v4.1.8.

[victorloux]

Hi, I'm still having the same problem despite using the latest version (v4.1.14 20/Mar/2017).

Running brew file init or init:

Traceback (most recent call last):
  File "/usr/local/bin/brew-file", line 3251, in <module>
    main()
  File "/usr/local/bin/brew-file", line 3248, in main
    b.execute()
  File "/usr/local/bin/brew-file", line 2875, in execute
    self.initialize()
  File "/usr/local/bin/brew-file", line 1834, in initialize
    "((n) for local Brewfile).")
  File "/usr/local/bin/brew-file", line 883, in ask_yn
    yn = my_input(question + " [y/n]: ").lower()
  File "/usr/local/bin/brew-file", line 60, in my_input
    return _input(word)
UnboundLocalError: local variable '_input' referenced before assignment

I sort of got a workaround working it by changing the shebang, to force using python2 instead of python3. Let me know if I can give you any other thing that could help you.

[rcmdnk]

yes, sry, I put another bug...

I'v fixed and v4.1.15 must be fine...

[victorloux]

Thanks for the quick reply! It works now.