Limnoria/src/utils/python.py

###
# Copyright (c) 2005, Jeremiah Fincher
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions, and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions, and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#   * Neither the name of the author of this software nor the name of
#     contributors to this software may be used to endorse or promote products
#     derived from this software without specific prior written consent.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
###

import types
import threading

def changeFunctionName(f, name, doc=None):
    if doc is None:
        doc = f.__doc__
    newf = types.FunctionType(f.func_code, f.func_globals, name,
                              f.func_defaults, f.func_closure)
    newf.__doc__ = doc
    return newf

class Object(object):
    def __ne__(self, other):
        return not self == other
    

class TupleSubclass(type):
    def __new__(cls, name, bases, dict):
        assert tuple in bases
        assert '__attrs__' in dict
        for (i, attr) in enumerate(dict['__attrs__']):
            dict[attr] = property(lambda self, i=i: self[i])
        del dict['__attrs__']
        # XXX Check the length of the iterable given.
        return super(TupleSubclass, cls).__new__(cls, name, bases, dict)
        
        
class Acquire(object):
    # Mixin for acquiring attributes from parents.
    def __init__(self, attr):
        self.__parent = attr

    def __getattr__(self, attr):
        return getattr(self.__parent, attr)
    

class Synchronized(type):
    def __new__(cls, name, bases, dict):
        sync = set()
        for base in bases:
            if hasattr(base, '__synchronized__'):
                sync.update(base.__synchronized__)
        if '__synchronized__' in dict:
            sync.update(dict['__synchronized__'])
        if sync:
            def synchronized(f):
                def g(self, *args, **kwargs):
                    self._Synchronized_rlock.acquire()
                    try:
                        f(self, *args, **kwargs)
                    finally:
                        self._Synchronized_rlock.release()
                return changeFunctionName(g, f.func_name, f.__doc__)
            for attr in sync:
                if attr in dict:
                    dict[attr] = synchronized(dict[attr])
            original__init__ = dict.get('__init__')
            def __init__(self, *args, **kwargs):
                if not hasattr(self, '_Synchronized_rlock'):
                    self._Synchronized_rlock = threading.RLock()
                if original__init__:
                    original__init__(self, *args, **kwargs)
                else:
                    # newclass is defined below.
                    super(newclass, self).__init__(*args, **kwargs)
            dict['__init__'] = __init__
        newclass = super(Synchronized, cls).__new__(cls, name, bases, dict)
        return newclass
                    
                
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