scons lint

[derekriemer]

I propose a linter to be built into NVDA's scons fscontruct file. Here are reasons I feel this way.

1. Code reviews already take a while to complete.
2. Once complete, the code review can be held up by contributers having to fix simple things like "x=4" to "x = 4"
3. A whole step could be taken from the equation, and NVDA's source code could be much cleaner indeed if a linter were included in NVDA's development packages.
4. Adding a note to the contributers guide, telling people to simply run scons lint before they make a PR, because code reviews that don't pass scons lint won't be excepted.

For background knowledge, a linter is a program that does static analysis of code, to ensure quality by forcing a certain structure. I believe linters can either fix the errors for you, or can give an error like
"c:\users\derek\nvda\source\browseMode.py 55:3,
Illegal use of spaces around equals signs, ensure a space is padding both sides of an equals sign instead"
This both improves the quality of code, and helps to ensure that code reviews take less time.

References:

PyLint
[What are the comprehensive lint checkers for python | stack overflow](http://stackoverflow.com/questions/5611776/what-are-the-comprehensive-lint-che
ckers-for-python)

[ctoth]

I agree this is a fantastic idea.
I've had good experiences with Flake8 https://pypi.python.org/pypi/flake8
You'd need to ship a default config that didn't complain about some of the most-common pep8 violations in NVDA source though.

[LeonarddeR]

@bramd: You might be interested in this issue.

[bramd]

Good idea. However, to get this right we might need to define the wanted code style first. Current NVDA source can be quite inconsistent. I don't do NVDA work that often and do other Python development as well. For other projects I've to comply with pep8, where NVDA deviates from that on various points, including indentation and name casing. So, a linter would help me a lot to follow NVDA's code style. I think this might also be the same for other Python devs that might contribute code from time to time. When using an editor with integrated linting support, the inline warning/errors really help me to get the code style right.

[Adriani90]

cc: @michaelDCurran, @feerrenrut