root / logilab.pylintinstaller / logilab / common / decorators.py

# 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.,
# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
"""this module contains some function/method decorators

:author:    Logilab
:copyright: 2006-2008 LOGILAB S.A. (Paris, FRANCE)
:contact:   http://www.logilab.fr/ -- mailto:python-projects@logilab.org
"""
__docformat__ = "restructuredtext en"

# XXX rewrite so we can use the decorator syntax when keyarg has to be specified

def cached(callableobj, keyarg=None):
    """simple decorator to cache result of method call"""
    #print callableobj, keyarg, callableobj.func_code.co_argcount
    if callableobj.func_code.co_argcount == 1 or keyarg == 0:
        
        def cache_wrapper1(self, *args):
            cache = '_%s_cache_' % callableobj.__name__
            #print 'cache1?', cache
            try:
                return self.__dict__[cache]
            except KeyError:
                #print 'miss'
                value = callableobj(self, *args)
                setattr(self, cache, value)
                return value
        return cache_wrapper1
    
    elif keyarg:
        
        def cache_wrapper2(self, *args, **kwargs):
            cache = '_%s_cache_' % callableobj.__name__
            key = args[keyarg-1]
            #print 'cache2?', cache, self, key
            try:
                _cache = self.__dict__[cache]
            except KeyError:
                #print 'init'
                _cache = {}
                setattr(self, cache, _cache)
            try:
                return _cache[key]
            except KeyError:
                #print 'miss', self, cache, key
                _cache[key] = callableobj(self, *args, **kwargs)
            return _cache[key]
        return cache_wrapper2

    def cache_wrapper3(self, *args):
        cache = '_%s_cache_' % callableobj.__name__
        #print 'cache3?', cache, self, args
        try:
            _cache = self.__dict__[cache]
        except KeyError:
            #print 'init'
            _cache = {}
            setattr(self, cache, _cache)
        try:
            return _cache[args]
        except KeyError:
            #print 'miss'
            _cache[args] = callableobj(self, *args)
        return _cache[args]
    return cache_wrapper3

def clear_cache(obj, funcname):
    """function to clear a cache handled by the cached decorator"""
    try:
        del obj.__dict__['_%s_cache_' % funcname]
    except KeyError:
        pass

def copy_cache(obj, funcname, cacheobj):
    """copy cache for <funcname> from cacheobj to obj"""
    cache = '_%s_cache_' % funcname
    try:
        setattr(obj, cache, cacheobj.__dict__[cache])
    except KeyError:
        pass


class wproperty(object):
    """simple descriptor expecting to take a modifier function as first argument
    and looking for a _<function name> to retreive the attribute
    """
    def __init__(self, setfunc):
        self.setfunc = setfunc
        self.attrname = '_%s' % setfunc.__name__
        
    def __set__(self, obj, value):
        self.setfunc(obj, value)
        
    def __get__(self, obj, cls):
        assert obj is not None
        return getattr(obj, self.attrname)


class classproperty(object):
    def __init__(self, get):
        self.get = get
    def __get__(self, inst, cls):
        return self.get(cls)

from time import clock
def timed(f):
    def wrap(*args, **kwargs):
        t = clock()
        #for i in range(100):
        res = f(*args, **kwargs)
        print '%s time: %.9f' % (f.__name__, clock() - t)
        return res
    return wrap