[MRG] remove py2 support

[teonbrooks]

PR to remove py2 support from mne-bids. mne-python has removed compatibility for py2 and we depend on it. we no longer have mne.externals.six to maintain compatibility.

[teonbrooks]

closes #140

[codecov-io]

Codecov Report

Merging #141 into master will decrease coverage by <.01%.
The diff coverage is 90%.

@@            Coverage Diff             @@
##           master     #141      +/-   ##
==========================================
- Coverage   94.38%   94.37%   -0.01%     
==========================================
  Files          14       14              
  Lines         979      978       -1     
==========================================
- Hits          924      923       -1     
  Misses         55       55

Impacted Files	Coverage Δ
mne_bids/mne_bids.py	94.25% <100%> (ø)	⬆️
mne_bids/datasets.py	70.73% <100%> (ø)	⬆️
mne_bids/tests/test_mne_bids.py	100% <100%> (ø)	⬆️
mne_bids/utils.py	92.7% <86.66%> (-0.04%)	⬇️

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[jasmainak]

Can you add a note to the readme that we support only Python 3 now?

[monkeyman192]

I can't make review comments in the right places, but there are a few places where we should migrate to my py3-thonic code:

mne-bids/mne_bids/utils.py

Line 57 in e26de96

except OSError as exc: # Python >2.5

Also,

mne-bids/mne_bids/utils.py

Line 350 in e26de96

raise OSError(errno.EEXIST, '"%s" already exists. Please set '

and

mne-bids/mne_bids/utils.py

Line 366 in e26de96

raise OSError(errno.EEXIST, '"%s" already exists. Please set '

should raise FileExistsError (and some tests etc will need to be updated to reflect this correctly...)

These are just a few I can think of from a quick scan but there are probably more.
If you think these changes are more appropriate to be in a separate PR I can make one to update some older code for py2 compatibility to nice py3 code...

[sappelhoff]

If you think these changes are more appropriate to be in a separate PR I can make one to update some older code for py2 compatibility to nice py3 code...

@monkeyman192, if @teonbrooks is fine with it, you can also send a PR to teonbrooks:py2-deletion so that these changes are directly included here.

Also, we should be explicit about which python 3 version, ... 3.6?

[monkeyman192]

I normally spec my code for about 3.4 at the earliest (because I am still running 3.4 on one or two of my machines), however I don't think there is really anything in here that would really change across 3.x versions (other than maybe changing pathing things to path-like objects instead of simply strings which was 3.6 iirc)
It's the weekend now, so I'll look into it on monday :P

[teonbrooks]

@monkeyman192, if @teonbrooks is fine with it, you can also send a PR to teonbrooks:py2-deletion so that these changes are directly included here.

PRs are definitely welcome. I don't know what the more pythonic way would be for those blocks of code you mentioned.

Also, we should be explicit about which python 3 version, ... 3.6?

I agree, we should list a minimum python version. is it 3.4 or 3.6?

[jasmainak]

Also, we should be explicit about which python 3 version, ... 3.6?

I think we should support all of Python 3 if it's not too much work. It's just nicer for the users if it doesn't come at an extra cost of code complexity. Otherwise, they will have to switch environments just to use mne-bids ...

[jasmainak]

I would say python 3 ... so we sync with MNE

[teonbrooks]

@jasmainak, if we do want all version of Python 3, should we change the environment to a lower version?

[jasmainak]

you read my mind. I was thinking the same ...

[teonbrooks]

it seems that mne is using 3.6 even though it generically states py3. also travis and appveyor yelled about 3.0 not being found. i will be revert back to 3.6

[jasmainak]

maybe we don't need to be worried about other python versions if mne is not worried ...

[jasmainak]

@teonbrooks you still need to address @monkeyman192 's comments

[teonbrooks]

@teonbrooks you still need to address @monkeyman192 's comments

I did. #141 (comment). It should be a separate pr because making the code more py3 pythonic isn't a blocker for remove py2 support.
I don't know what is to be done since it is @monkeyman192's approach. I can wait for his pr to this branch before this is merged. I tend to like short, focused prs

[jasmainak]

you just need to replace all occurences of errno.EEXIST with FileExists error. I think it's simple enough not to warrant a new PR, but as you like ...

[teonbrooks]

you just need to replace all occurences of errno.EEXIST with FileExists error. I think it's simple enough not to warrant a new PR, but as you like ...

ok, added those. I just assumed that there were more py3ism that were to be implemented so I was just going to save them all. I updated to account for that find/replace.

[jasmainak]

Good to go on my end.

[sappelhoff]

thanks @teonbrooks! :-)

[monkeyman192]

ok, added those. I just assumed that there were more py3ism that were to be implemented so I was just going to save them all. I updated to account for that find/replace.

Oh yeah, my comment was more of a general one about the possibility of updating any code that could be nicer using python 3 syntax/functions.
I'll have a look through the code at some point and see if there are any things that can be made a bit nicer and just make a separate PR if it looks like it is worth changing anything.

Edit: Ok, there were a few little things to fix, nothing major, but I made it a little bit cleaner I think... Should I make a separate PR or something else? (it's only a few small changes...)(cf. monkeyman192@6fdfe2b)

[teonbrooks]

Edit: Ok, there were a few little things to fix, nothing major, but I made it a little bit cleaner I think... Should I make a separate PR or something else? (it's only a few small changes...)(cf. monkeyman192@6fdfe2b)

@monkeyman192 yes, a separate pr would be great