[Python-projects] pylint: Crash on module-level @staticmethod/@classmethod

[Maarten ter Huurne]

Hi,

When running pylint on this program:

===
@staticmethod
def f():
      pass
===

I get the following exception trace:
===
Traceback (most recent call last):
  File "/usr/bin/pylint", line 4, in <module>
    lint.Run(sys.argv[1:])
  File "/usr/lib/python2.5/site-packages/pylint/lint.py", line 901, in
__init__
    linter.check(args)
  File "/usr/lib/python2.5/site-packages/pylint/lint.py", line 492, in
check
    self.check_astng_module(astng, checkers)
  File "/usr/lib/python2.5/site-packages/pylint/lint.py", line 602, in
check_astng_module
    if implements(checker, IASTNGChecker)])
  File "/usr/lib/python2.5/site-packages/pylint/lint.py", line 619, in
astng_events
    self.astng_events(child, checkers, _reversed_checkers)
  File "/usr/lib/python2.5/site-packages/pylint/lint.py", line 619, in
astng_events
    self.astng_events(child, checkers, _reversed_checkers)
  File "/usr/lib/python2.5/site-packages/pylint/lint.py", line 616, in
astng_events
    checker.visit(astng)
  File "/usr/lib/python2.5/site-packages/logilab/astng/utils.py", line 84,
in visit
    method(node)
  File "/usr/lib/python2.5/site-packages/pylint/checkers/classes.py", line
206, in visit_function
    self._check_first_arg_for_type(node, klass.type == 'metaclass')
AttributeError: Module instance has no attribute 'type'
===

Although it is a bit unusual to have a static method at the module level,
the Python interpreter accepts it.

The same crash happens on @classmethod when used at the model level.

I had a look at checkers/classes.py to see if fixing it would be easy, but
it wasn't clear to me what the proper approach would be:
- let is_method() should return False in cases like this
- don't assume that a method's parent is always a class

As a quick fix, I settled on the latter:
      klass_type = getattr(klass, 'type', None) # "klass" might not be a
class
And replace "klass.type" by "klass_type", once in checkers/classes.py and
once in checkers/variables.py.

Versions used:
pylint 0.14.0,
astng 0.17.2, common 0.22.1
Python 2.5.1 (r251:54863, Mar  7 2008, 03:41:45)

Bye,
            Maarten
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