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"""
The LLVM Compiler Infrastructure
This file is distributed under the University of Illinois Open Source
License. See LICENSE.TXT for details.
Provides classes used by the test results reporting infrastructure
within the LLDB test suite.
This module contains utilities used by the lldb test framwork.
"""
class OptionalWith(object):
# pylint: disable=too-few-public-methods
# This is a wrapper - it is not meant to provide any extra methods.
"""Provides a wrapper for objects supporting "with", allowing None.
This lets a user use the "with object" syntax for resource usage
(e.g. locks) even when the wrapped with object is None.
e.g.
wrapped_lock = OptionalWith(thread.Lock())
with wrapped_lock:
# Do something while the lock is obtained.
pass
might_be_none = None
wrapped_none = OptionalWith(might_be_none)
with wrapped_none:
# This code here still works.
pass
This prevents having to write code like this when
a lock is optional:
if lock:
lock.acquire()
try:
code_fragament_always_run()
finally:
if lock:
lock.release()
And I'd posit it is safer, as it becomes impossible to
forget the try/finally using OptionalWith(), since
the with syntax can be used.
"""
def __init__(self, wrapped_object):
self.wrapped_object = wrapped_object
def __enter__(self):
if self.wrapped_object is not None:
return self.wrapped_object.__enter__()
else:
return self
def __exit__(self, the_type, value, traceback):
if self.wrapped_object is not None:
return self.wrapped_object.__exit__(the_type, value, traceback)
else:
# Don't suppress any exceptions
return False
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