Yury Selivanov wrote:
BTW we already have mechanisms to always propagate context to the caller -- just use threading.local() or a global variable.
But then you don't have a way to *not* propagate the context change when you don't want to. Here's my suggestion: Make an explicit distinction between creating a new binding for a context var and updating an existing one. So instead of two API calls there would be three: contextvar.new(value) # Creates a new binding only # visible to this frame and # its callees contextvar.set(value) # Updates existing binding in # context inherited from caller contextvar.get() # Retrieves the current binding If we assume an extension to the decimal module so that decimal.localcontext is a context var, we can now do this: async def foo(): # Establish a new context for this task decimal.localcontext.new(decimal.Context()) # Delegate changing the context await bar() # Do some calculations yield 17 * math.pi + 42 async def bar(): # Change context for caller decimal.localcontext.prec = 5 -- Greg _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com