Global objects in Perspective Scope

Ignition
13

Replace it unconditionally in the top level of the defining script. Something like this:

class myClass():
	__init__(self, prior):
		# Copy important values from prior version, as long as they
		# are platform data types.  Stop any threads stored in prior
		# and remove any of its listeners from the platform.
		pass

# Get the persistent global dictionary
_g = system.util.getGlobals()

# Protect the swap with a lock.  Locks are defined by
# the jython stdlib, so do not have to be replaced on restarts.
# Use setdefault for assignment to ensure atomicity.
singletonLock = _g.get('singletonLock', None)
if singletonLock is None:
	import thread
	singletonLock = _g.setdefault('singletonLock', thread.allocate_lock())

# Swap old and new under the lock.  This prevents
# races amongst multiple scripting contexts importing this script
# simultaneously.  Just note that a new version might be replaced by
# another script context as soon as the lock is released.
with singletonLock:
	_g['singletonKey'] = myClass(_g.get('singletonKey', None))

# Use the following pattern in functions where you need to use the
# singleton.  Whatever you do, never sleep or do long calculations
# while holding the lock.

# with singletonLock:
#     c = _g[singletonKey]
#     # Do something with c
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