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gh-142119: Clarify that one contextvars.Token can only reset once in a lifetime #143693

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gh-142119: Clarify that one contextvars.Token can only reset once in a lifetime #143693

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0e18375
Clarify that `contextvar.Token` objects are for single use
johnslavik Jan 11, 2026
c29b7ec
Preserve spacing between sections
johnslavik Jan 11, 2026
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4 changes: 3 additions & 1 deletion Doc/library/contextvars.rst
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Expand Up @@ -93,13 +93,15 @@ Context Variables
# After the reset call the var has no value again, so
# var.get() would raise a LookupError.

The same *token* cannot be used twice.


.. class:: Token

*Token* objects are returned by the :meth:`ContextVar.set` method.
They can be passed to the :meth:`ContextVar.reset` method to revert
the value of the variable to what it was before the corresponding
*set*.
*set*. A single token cannot reset a context variable more than once.

The token supports :ref:`context manager protocol <context-managers>`
to restore the corresponding context variable value at the exit from
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