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# -*- coding: utf-8 -*-
#
# File: portato/backend/__init__.py
# This file is part of the Portato-Project, a graphical portage-frontend.
#
# Copyright (C) 2006-2010 René 'Necoro' Neumann
# This is free software. You may redistribute copies of it under the terms of
# the GNU General Public License version 2.
# There is NO WARRANTY, to the extent permitted by law.
#
# Written by René 'Necoro' Neumann <necoro@necoro.net>
from __future__ import absolute_import
from ..helper import debug
from .system_interface import SystemInterface
from .exceptions import BlockedException, PackageNotFoundException, DependencyCalcError, InvalidSystemError
class _Package (object):
"""Wrapping class from which L{portato.backend.Package} inherits. This is used by the flags module to check
whether an object is a package. It cannot use the normal Package class as this results in cyclic dependencies."""
def __init__ (self):
raise TypeError, "Calling __init__ on portato.backend._Package objects is not allowed."
def is_package(what):
return isinstance(what, _Package)
class SystemWrapper (SystemInterface):
"""This is a wrapper to the different system interfaces, allowing the direct import via C{from portato.backend import system}.
With this wrapper a change of the system is propagated to all imports."""
__system = 'portage'
__wrapped_sys = None
__slots__ = ('__system', '__wrapped_sys', 'set_system', '__load')
def __getattribute__ (self, name):
"""Just pass all attribute accesses directly to _sys."""
if name in SystemWrapper.__slots__:
return object.__getattribute__(self, name)
if SystemWrapper.__wrapped_sys is None:
SystemWrapper.__load()
return getattr(SystemWrapper.__wrapped_sys, name)
@classmethod
def set_system (cls, system):
"""Sets the current system to a new one.
@param system: the name of the system to take
@type system: string"""
cls.__system = system
cls.__wrapped_sys = None
@classmethod
def __load (cls):
"""Loads the current chosen system.
@raises InvalidSystemError: if an inappropriate system is set"""
if cls.__system == "portage":
debug("Setting Portage System")
from .portage import PortageSystem
cls.__wrapped_sys = PortageSystem ()
else:
raise InvalidSystemError, cls.__system
system = SystemWrapper()
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