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# Copyright (c) 2007, Riverbank Computing Limited
# All rights reserved.
# This software is provided without warranty under the terms of the BSD
# license included in enthought/LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license. The license
# is also available online at
# Standard library imports.
import os
import sys
# Enthought library imports.
from traits.etsconfig.api import ETSConfig
# This is set to the root part of the module path for the selected backend.
_toolkit_backend = None
def _init_toolkit():
""" Initialise the current toolkit. """
def import_toolkit(tk):
# Try and import the toolkit's pyface backend init module.
be = 'pyface.ui.%s.' % tk
__import__(be + 'init')
return be
# Get the toolkit.
if ETSConfig.toolkit:
be = import_toolkit(ETSConfig.toolkit)
# Toolkits to check for if none is explicitly specified.
known_toolkits = ('wx', 'qt4', 'null')
for tk in known_toolkits:
be = import_toolkit(tk)
# In case we have just decided on a toolkit, tell everybody else.
ETSConfig.toolkit = tk
except (SystemExit, ImportError):
import traceback
print >>sys.stderr, ('Warning: Unable to import the %s backend '
'for pyface due to traceback: %s\n') % (tk,
traceback.format_exc().strip().replace('\n', '\n\t'))
# Try to import the null toolkit but don't set the ETSConfig toolkit
be = import_toolkit('null')
print >>sys.stderr, ("Info: Unable to import any backend (%s) "
"for pyface; using the 'null' toolkit instead.\n") % ", ".join(known_toolkits)
raise ImportError("Unable to import a pyface backend for any "
"of the %s toolkits" % ", ".join(known_toolkits))
# Save the imported toolkit module.
global _toolkit_backend
_toolkit_backend = be
# Do this once then disappear.
del _init_toolkit
def toolkit_object(name):
""" Return the toolkit specific object with the given name. The name
consists of the relative module path and the object name separated by a
mname, oname = name.split(':')
be_mname = _toolkit_backend + mname
class Unimplemented(object):
""" This is returned if an object isn't implemented by the selected
toolkit. It raises an exception if it is ever instantiated.
def __init__(self, *args, **kwargs):
raise NotImplementedError("the %s pyface backend doesn't implement %s" % (ETSConfig.toolkit, oname))
be_obj = Unimplemented
be_obj = getattr(sys.modules[be_mname], oname)
except AttributeError:
except ImportError, e:
# Ignore *ANY* errors unless a debug ENV variable is set.
if 'ETS_DEBUG' in os.environ:
# Attempt to only skip errors in importing the backend modules.
# The idea here is that this only happens when the last entry in
# the traceback's stack frame mentions the toolkit in question.
import traceback
frames = traceback.extract_tb(sys.exc_traceback)
filename, lineno, function, text = frames[-1]
if not _toolkit_backend in filename:
return be_obj
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