Syntastic: feature request: syntax check support for Python 3

[stardiviner]

Just like the title write, I hope Syntastic support Python 3.

[daniel-walker]

Doesn't it already have support ? It uses a couple different python checkers, I would think at least one supports Python 3.

[phanimahesh]

I find that syntastic shows an error with the print function (python3) but is happy with the old syntax.
Do I have to do something to tell syntastic that I am working with python3?

[lcd047]

@phanimahesh: You tell us. :) There are two potential problems with the python checker:

1. you might get the (in)famous E40 error when checking a file with unusual characters in the name;
2. some errors are not recognized.
   Please post a bug report if you run into any of them.

[phanimahesh]

@lcd047 I have a different problem.

• The file name has no unusual characters and I do not enounter E40.
• Something that is _not_ an error is being detected as one.

# This is detected as a syntax error, but is valid python3
print('Just Testing',file=sys.stderr)

So my question is:

• Does syntastic really support python3? (Answered yes before this issue was closed.)
• How does syntastic know if I'm working with python2 or python3? ( What is the detection algorithm, if there is one?)
• Can I override it? ( Syntastic detects python2 but I want to treat my file as python3, or vice-versa)

[lcd047]

Syntastic doesn't care about python versions, it just calls a program named python, and tries to parse whatever errors that program produces. You can, of course, override it:

let g:syntastic_python_python_exe = 'python3'

[phanimahesh]

Thanks. That solved my issues. :)

[0xl3x1]

Note you should actually be setting g:syntastic_python_python_exec, NOT g:syntastic_python_python_exe (as per here):

let g:syntastic_python_python_exec = 'python3'

[lcd047]

Using g:syntastic_python_python_exe was appropriate at the time, for a brief while; it no longer is for recent versions of syntastic. Which is why you should read the manual, or at least the FAQ before searching the archives: old advice might be outdated.

[0xl3x1]

@lcd047 Indeed. Unfortunately this is the first result on Google when searching for "python3 syntastic", so it's probably worthwhile making the point explicitly.

[lcd047]

There also seems to be a widespread confusion about it on StackOverflow. The exe thing is rarely useful outside syntastic code itself, it should probably be renamed to something else. Sadly doing so would break a few third-party checkers, and checking syntastic version is also awkward, for similar historic reasons.