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#!/usr/bin/env python
#############################################################################
##
## This file is part of Taurus
##
## http://taurus-scada.org
##
## Copyright 2011 CELLS / ALBA Synchrotron, Bellaterra, Spain
##
## Taurus is free software: you can redistribute it and/or modify
## it under the terms of the GNU Lesser General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## Taurus 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 Lesser General Public License for more details.
##
## You should have received a copy of the GNU Lesser General Public License
## along with Taurus. If not, see <http://www.gnu.org/licenses/>.
##
#############################################################################
'''
Examples on using the evaluation scheme for exposing arbitrary non-tango quantities as taurus attributes
'''
__all__ = ['FreeSpaceDevice']
from taurus.core.evaluation import EvaluationDevice
import os, platform, ctypes
class FreeSpaceDevice(EvaluationDevice):
'''A simple example of usage of the evaluation scheme for
creating a device that allows to obtain available space in a dir.
Important: note that only those members listed in `_symbols` will be available
'''
_symbols = ['getFreeSpace']
def getFreeSpace(self, dir):
""" return free space (in bytes).
(Recipe adapted from `http://stackoverflow.com/questions/51658`)
"""
if platform.system() == 'Windows':
free_bytes = ctypes.c_ulonglong(0)
ctypes.windll.kernel32.GetDiskFreeSpaceExW(ctypes.c_wchar_p(dir), None, None, ctypes.pointer(free_bytes))
return free_bytes.value
else:
s = os.statvfs(dir)
return s.f_bsize * s.f_bavail
#===============================================================================
# Just for testing
#===============================================================================
def test1():
import taurus
a = taurus.Attribute('eval://dev=taurus.core.evaluation.dev_example.FreeSpaceDevice;getFreeSpace("/")/1024/1024') #calculates free space in Mb
print "Free space: %iMb"%a.read().value
def test2():
import sys
from taurus.qt.qtgui.application import TaurusApplication
from taurus.qt.qtgui.display import TaurusLabel
app = TaurusApplication()
w = TaurusLabel()
attrname='eval://dev=taurus.core.evaluation.dev_example.FreeSpaceDevice;getFreeSpace("/")' #calculates free space in Mb
w.setModel(attrname)
w.show()
sys.exit(app.exec_())
if __name__ == "__main__":
test2()
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