A very small and simple usage mechanism for Python threadlocals.

A very small and simple usage mechanism for Python threadlocals.

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.

Example Usage

Instantiating

The Chipmunk object is a sort of singleton that is instantiated upon import.

from chipmunk import Chipmunk #  Ready for use

Storing Data

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

Retrieving Data

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")

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