# Copyright (c) 2003-2013 LOGILAB S.A. (Paris, FRANCE).
# http://www.logilab.fr/ -- mailto:[email protected]
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
"""check for signs of poor design"""
import re
from collections import defaultdict
from astroid import Function, If, InferenceError
from pylint.interfaces import IAstroidChecker
from pylint.checkers import BaseChecker
from pylint.checkers.utils import check_messages
# regexp for ignored argument name
IGNORED_ARGUMENT_NAMES = re.compile('_.*')
def class_is_abstract(klass):
"""return true if the given class node should be considered as an abstract
class
"""
for attr in klass.values():
if isinstance(attr, Function):
if attr.is_abstract(pass_is_abstract=False):
return True
return False
MSGS = {
'R0901': ('Too many ancestors (%s/%s)',
'too-many-ancestors',
'Used when class has too many parent classes, try to reduce \
this to get a simpler (and so easier to use) class.'),
'R0902': ('Too many instance attributes (%s/%s)',
'too-many-instance-attributes',
'Used when class has too many instance attributes, try to reduce \
this to get a simpler (and so easier to use) class.'),
'R0903': ('Too few public methods (%s/%s)',
'too-few-public-methods',
'Used when class has too few public methods, so be sure it\'s \
really worth it.'),
'R0904': ('Too many public methods (%s/%s)',
'too-many-public-methods',
'Used when class has too many public methods, try to reduce \
this to get a simpler (and so easier to use) class.'),
'R0911': ('Too many return statements (%s/%s)',
'too-many-return-statements',
'Used when a function or method has too many return statement, \
making it hard to follow.'),
'R0912': ('Too many branches (%s/%s)',
'too-many-branches',
'Used when a function or method has too many branches, \
making it hard to follow.'),
'R0913': ('Too many arguments (%s/%s)',
'too-many-arguments',
'Used when a function or method takes too many arguments.'),
'R0914': ('Too many local variables (%s/%s)',
'too-many-locals',
'Used when a function or method has too many local variables.'),
'R0915': ('Too many statements (%s/%s)',
'too-many-statements',
'Used when a function or method has too many statements. You \
should then split it in smaller functions / methods.'),
'R0921': ('Abstract class not referenced',
'abstract-class-not-used',
'Used when an abstract class is not used as ancestor anywhere.'),
'R0922': ('Abstract class is only referenced %s times',
'abstract-class-little-used',
'Used when an abstract class is used less than X times as \
ancestor.'),
'R0923': ('Interface not implemented',
'interface-not-implemented',
'Used when an interface class is not implemented anywhere.'),
}
class MisdesignChecker(BaseChecker):
"""checks for sign of poor/misdesign:
* number of methods, attributes, local variables...
* size, complexity of functions, methods
"""
__implements__ = (IAstroidChecker,)
# configuration section name
name = 'design'
# messages
msgs = MSGS
priority = -2
# configuration options
options = (('max-args',
{'default' : 5, 'type' : 'int', 'metavar' : '<int>',
'help': 'Maximum number of arguments for function / method'}
),
('ignored-argument-names',
{'default' : IGNORED_ARGUMENT_NAMES,
'type' :'regexp', 'metavar' : '<regexp>',
'help' : 'Argument names that match this expression will be '
'ignored. Default to name with leading underscore'}
),
('max-locals',
{'default' : 15, 'type' : 'int', 'metavar' : '<int>',
'help': 'Maximum number of locals for function / method body'}
),
('max-returns',
{'default' : 6, 'type' : 'int', 'metavar' : '<int>',
'help': 'Maximum number of return / yield for function / '
'method body'}
),
('max-branches',
{'default' : 12, 'type' : 'int', 'metavar' : '<int>',
'help': 'Maximum number of branch for function / method body'}
),
('max-statements',
{'default' : 50, 'type' : 'int', 'metavar' : '<int>',
'help': 'Maximum number of statements in function / method '
'body'}
),
('max-parents',
{'default' : 7,
'type' : 'int',
'metavar' : '<num>',
'help' : 'Maximum number of parents for a class (see R0901).'}
),
('max-attributes',
{'default' : 7,
'type' : 'int',
'metavar' : '<num>',
'help' : 'Maximum number of attributes for a class \
(see R0902).'}
),
('min-public-methods',
{'default' : 2,
'type' : 'int',
'metavar' : '<num>',
'help' : 'Minimum number of public methods for a class \
(see R0903).'}
),
('max-public-methods',
{'default' : 20,
'type' : 'int',
'metavar' : '<num>',
'help' : 'Maximum number of public methods for a class \
(see R0904).'}
),
)
def __init__(self, linter=None):
BaseChecker.__init__(self, linter)
self.stats = None
self._returns = None
self._branches = None
self._used_abstracts = None
self._used_ifaces = None
self._abstracts = None
self._ifaces = None
self._stmts = 0
def open(self):
"""initialize visit variables"""
self.stats = self.linter.add_stats()
self._returns = []
self._branches = defaultdict(int)
self._used_abstracts = {}
self._used_ifaces = {}
self._abstracts = []
self._ifaces = []
# Check 'R0921', 'R0922', 'R0923'
def close(self):
"""check that abstract/interface classes are used"""
for abstract in self._abstracts:
if not abstract in self._used_abstracts:
self.add_message('abstract-class-not-used', node=abstract)
elif self._used_abstracts[abstract] < 2:
self.add_message('abstract-class-little-used', node=abstract,
args=self._used_abstracts[abstract])
for iface in self._ifaces:
if not iface in self._used_ifaces:
self.add_message('interface-not-implemented', node=iface)
@check_messages('too-many-ancestors', 'too-many-instance-attributes',
'too-few-public-methods', 'too-many-public-methods',
'abstract-class-not-used', 'abstract-class-little-used',
'interface-not-implemented')
def visit_class(self, node):
"""check size of inheritance hierarchy and number of instance attributes
"""
# Is the total inheritance hierarchy is 7 or less?
nb_parents = len(list(node.ancestors()))
if nb_parents > self.config.max_parents:
self.add_message('too-many-ancestors', node=node,
args=(nb_parents, self.config.max_parents))
# Does the class contain less than 20 attributes for
# non-GUI classes (40 for GUI)?
# FIXME detect gui classes
if len(node.instance_attrs) > self.config.max_attributes:
self.add_message('too-many-instance-attributes', node=node,
args=(len(node.instance_attrs),
self.config.max_attributes))
# update abstract / interface classes structures
if class_is_abstract(node):
self._abstracts.append(node)
elif node.type == 'interface' and node.name != 'Interface':
self._ifaces.append(node)
for parent in node.ancestors(False):
if parent.name == 'Interface':
continue
self._used_ifaces[parent] = 1
try:
for iface in node.interfaces():
self._used_ifaces[iface] = 1
except InferenceError:
# XXX log ?
pass
for parent in node.ancestors():
try:
self._used_abstracts[parent] += 1
except KeyError:
self._used_abstracts[parent] = 1
@check_messages('too-many-ancestors', 'too-many-instance-attributes',
'too-few-public-methods', 'too-many-public-methods',
'abstract-class-not-used', 'abstract-class-little-used',
'interface-not-implemented')
def leave_class(self, node):
"""check number of public methods"""
nb_public_methods = 0
for method in node.mymethods():
if not method.name.startswith('_'):
nb_public_methods += 1
# Does the class contain less than 20 public methods ?
if nb_public_methods > self.config.max_public_methods:
self.add_message('too-many-public-methods', node=node,
args=(nb_public_methods,
self.config.max_public_methods))
# stop here for exception, metaclass and interface classes
if node.type != 'class':
return
# Does the class contain more than 5 public methods ?
if nb_public_methods < self.config.min_public_methods:
self.add_message('too-few-public-methods', node=node,
args=(nb_public_methods,
self.config.min_public_methods))
@check_messages('too-many-return-statements', 'too-many-branches',
'too-many-arguments', 'too-many-locals',
'too-many-statements')
def visit_function(self, node):
"""check function name, docstring, arguments, redefinition,
variable names, max locals
"""
# init branch and returns counters
self._returns.append(0)
# check number of arguments
args = node.args.args
if args is not None:
ignored_args_num = len(
[arg for arg in args
if self.config.ignored_argument_names.match(arg.name)])
argnum = len(args) - ignored_args_num
if argnum > self.config.max_args:
self.add_message('too-many-arguments', node=node,
args=(len(args), self.config.max_args))
else:
ignored_args_num = 0
# check number of local variables
locnum = len(node.locals) - ignored_args_num
if locnum > self.config.max_locals:
self.add_message('too-many-locals', node=node,
args=(locnum, self.config.max_locals))
# init statements counter
self._stmts = 1
@check_messages('too-many-return-statements', 'too-many-branches',
'too-many-arguments', 'too-many-locals',
'too-many-statements')
def leave_function(self, node):
"""most of the work is done here on close:
checks for max returns, branch, return in __init__
"""
returns = self._returns.pop()
if returns > self.config.max_returns:
self.add_message('too-many-return-statements', node=node,
args=(returns, self.config.max_returns))
branches = self._branches[node]
if branches > self.config.max_branches:
self.add_message('too-many-branches', node=node,
args=(branches, self.config.max_branches))
# check number of statements
if self._stmts > self.config.max_statements:
self.add_message('too-many-statements', node=node,
args=(self._stmts, self.config.max_statements))
def visit_return(self, _):
"""count number of returns"""
if not self._returns:
return # return outside function, reported by the base checker
self._returns[-1] += 1
def visit_default(self, node):
"""default visit method -> increments the statements counter if
necessary
"""
if node.is_statement:
self._stmts += 1
def visit_tryexcept(self, node):
"""increments the branches counter"""
branches = len(node.handlers)
if node.orelse:
branches += 1
self._inc_branch(node, branches)
self._stmts += branches
def visit_tryfinally(self, node):
"""increments the branches counter"""
self._inc_branch(node, 2)
self._stmts += 2
def visit_if(self, node):
"""increments the branches counter"""
branches = 1
# don't double count If nodes coming from some 'elif'
if node.orelse and (len(node.orelse) > 1 or
not isinstance(node.orelse[0], If)):
branches += 1
self._inc_branch(node, branches)
self._stmts += branches
def visit_while(self, node):
"""increments the branches counter"""
branches = 1
if node.orelse:
branches += 1
self._inc_branch(node, branches)
visit_for = visit_while
def _inc_branch(self, node, branchesnum=1):
"""increments the branches counter"""
self._branches[node.scope()] += branchesnum
# FIXME: make a nice report...
def register(linter):
"""required method to auto register this checker """
linter.register_checker(MisdesignChecker(linter))
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