Description

vsc-install provides shared setuptools functions and classes for python libraries developed by UGent's HPC group

Common pitfalls

bdist_rpm will fail if your install_requires = 'setuptools' because it will fail to find a setuptools rpm.

export VSC_RPM_PYTHON=1

will make sure the python- prefix is added to the packages in install_requires for building RPM's so python-setuptools will be used.

Add tests

Test are python modules in the test directory which have subclass of TestCase and at least one method that has a name starting with test_

You are advised to use

from vsc.install.testing import TestCase

(instead of basic TestCase from unittest).

And any __main__ or suite() is not needed (anymore).

Initialise the test directory with

mkdir -p test
echo '' > test/__init__.py
echo 'from vsc.install.commontest import CommonTest' > test/00-import.py

When the tests are run, test, lib and bin (if relevant) are added to sys.path, so no need to do so in the tets modules.

Run tests

python setup.py test

Filter tests with -F (test module names) and -f (test method names)

Fix failing tests

Missing / incorrect LICENSE
Copy the appropirate license file under known_licenses in the project directory and name the file LICENSE
Missing README.md
Create a README.md file with at least a Description section

Fix license headers as described in https://github.com/hpcugent/vsc-install/blob/master/lib/vsc/install/headers.py

cd <project dir with .git folder>
REPO_BASE_DIR=$PWD python -m vsc.install.headers path/to/file script_or_not

Fix them all at once using find

find ./{lib,test} -type f -name '*.py' | REPO_BASE_DIR=$PWD xargs -I '{}' python -m vsc.install.headers '{}'
find ./bin -type f -name '*.py' | REPO_BASE_DIR=$PWD xargs -I '{}' python -m vsc.install.headers '{}' 1

Do not forget to check the diff

Python scripts (i.e. with a python shebang and installed as scripts in setup) have to use #!/usr/bin/env python as shebang
Remove any build_rpms_settings.sh leftovers
The TARGET dict in setup.py should be minimal unless you really know what you are doing (i.e. if it is truly different from defaults)
Remove name, scripts, ...
Exception: vsc namespace packages do not allow non-shared namespace
Add to the __init__.py

"""
Allow other packages to extend this namespace, zip safe setuptools style
"""
import pkg_resources
pkg_resources.declare_namespace(__name__)

bare-except

try:
   # something
except:

This is bad, because this except will also catch sys.exit() or Keyboardinterupts, something you typically do not want, if you catch these the program will be in a weird state and then continue on, whilst the person who just pressed ctrl+c is wondering what is going on and why it is not stopping.

so at the very least make this except Exception (which doesn't catch sys.exit and KeyboardInterupt) and it would be appreciated if you could actually figure out what exceptions to expect and only catch those and let your program crash if something you did not intend happens because it helps developers catch weird errors on their side better.

if you do something like

try:
    open(int(somestring)).write('important data')
except Exception:
    pass # if somestring is not an integer, we didn't need to write anyway, but otherwise we do

because you know sometimes this string does not contain an integer, so the int() call can fail you should really only catch ValueError, because this will also fail when your disk is full, or you don't have permissions or xxx other reasons, and the important data will not be written out and nobody will notice anything!

if not 'a' in somelist -> if 'a' not in somelist

this isn't that big of a deal, but if everyone is consistent it's less likely to introduce bugs when a not is added or removed where it didn't need to. Also helps code review, not in reads better, like english.

arguments-differ

this will give you errors if you override a function of a superclass but don't use the same amount of arguments, using less will surely give you errors, so the linter catches this for you now

unused-argument

if you have a function definition witch accepts an argument that is never used in the function body this will now give an error. clean up your function definition, or fix the error where you actually do need to take this argument into account

unused-variable

defining a variable and then not using it anymore smells bad, why did you do that? sometimes you do things like

out, exit_code = run_command(something)

but you are not interested in the out, only in the exit code, in this case, write

_, exit_code = run_command(something)

using _ as a variable name lets pylint and other readers know you do not intend to use that output in the first place.

reimported

when you re import a name somewhere else, usually this is just an import to much, or 2 imports with the same name, pay attention.

import six
from django import six

import six
from django import six as django_six

redefinition of unused name

this usually also points to something you did not expect

from vsc.accountpageclient import VscGroup
<snip>

class VscGroup(object):
    pass

=> do you need the import? use import as did you mean to use the same name? ...

unpacking-in-except / redefine-in-handler

Multiple exception have to be grouped in a tuple like

    ...
except (ExceptionOne, ExceptionTwo) ...
    ...

(espcially when used like except A, B: which should be except (A, B):.

turning off these errors

If in any of these cases you think: yes, I really needed to do this, I'm monkeypatching things, I'm adding extra functionality that does indeed have an extra(default) paramenter, etc, etc you can let pylint know to ignore this error in this one specific block of code by adding e.g. the comment # pylint: disable=<name or numeric id of pylint code>

class Something(object):
    def dosomething(self, some, thing):
        # do something

class MyFancyThing(SomeThing):
    # pylint: disable=arguments-differ
    def dosomething(self, some, thing, fancy=None):
         # do something fancy

Full list with all codes is available at http://pylint-messages.wikidot.com/all-codes

verdurin/vsc-install