This is an abstraction on type of threading.local
that attempts to simply usage a bit and combat the common
problem of accidentally overwriting values that may have been added by other portions of code. It also implements the
in
operator to test for inclusion and the bool() method to test whether the Chipmunk is holding anything.
The Chipmunk
object is a sort of singleton that is instantiated upon import.
from chipmunk import Chipmunk # Ready for use
Asking the Chipmunk
to hold something can be done in one of three ways:
Setting Attributes Directly
Chipmunk.acorn = "Acorn"
Chipmunk.acorn_count = 5
With the store_data
method
Chipmunk.store_data("acorn", "Acorn")
Chipmunk.store_data("acorn_count", 5)
And with a context manager for short-term storage that removes the need for checking whether it is already holding something with the given name.
Chipmunk.nut = "acorn"
with Chipmunk.hold_this("nut", "walnut"):
do_something_with_Chipmunk()
return Chipmunk.nut # Returns "acorn"
If the Chipmunk
is already holding something and you ask it to hold something else with the same name it will raise
an AttributeError. If you want to replace an object permanently you must call either the delete_data
or clear
methods or use del Chipmunk.attr
.
Chipmunk.nut = "acorn"
Chipmunk.nut = "walnut" # AttributeError thrown
Chipmunk.nut = "acorn"
del Chipmunk.nut
Chipmunk.nut = "walnut" # OK
Chipmunk.nut = "acorn"
Chipmunk.delete_data("nut")
Chipmunk.nut = "walnut" # OK
When retrieving data from the Chipmunk
a bool()
check will tell you if it's holding anything at all.
from chipmunk import Chipmunk
if Chipmunk: # Conditional fails
return "Not Empty"
Chipmunk.nut = "acorn"
if Chipmunk: # Conditional succeeds
return "Not Empty"
Testing whether the Chipmunk
is holding something with a given name is as simple as an in
check.
Chipmunk.nut = "acorn"
"nut" in Chipmunk # True
Data can be accessed by doing an attribute lookup directly, using the get_data
method, or getattr
.
Chipmunk.nut = "acorn"
# These all return "acorn"
Chipmunk.nut
Chipmunk.get_data("nut")
getattr(Chipmunk, "nut")