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ExpirationDate

is an option for various functions that specifies when a persistent value should be treated as expired.

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Basic Examples  
Properties & Relations  
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ExpirationDate

ExpirationDate

is an option for various functions that specifies when a persistent value should be treated as expired.

Details

  • ExpirationDate can be used for PersistentSymbol and InitializationValue.
  • Values can be given as absolute times or date and time specifications.
  • Numerical values are treated as values given by UnixTime.
  • The value Infinity (∞) or None can be used to specify that a persistent value should never expire.
  • An expired persistent value is treated as nonexistent, and the underlying persistent object may be removed.

Examples

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Basic Examples  (4)

Define a persistent value that expires at the beginning of the year 2024:

Wolfram Language code: PersistentSymbol["e1", ExpirationDate -> DateObject[{2024}]] = 1;

Verify the expiration date of the underlying persistent object:

Wolfram Language code: PersistentObject["e1", $PersistenceBase]["ExpirationDate"]

Define a persistent value that expires at the beginning of next year:

Wolfram Language code: PersistentSymbol["e2", ExpirationDate -> NextDate["Year"]] = 2;

Verify the expiration date of the underlying persistent object:

Wolfram Language code: PersistentObject["e2", $PersistenceBase]["ExpirationDate"]

Define a persistent value that expires immediately:

Wolfram Language code: PersistentSymbol["e3", ExpirationDate -> Now] = 2;

Accessing an expired persistent value behaves as if it did not exist:

Wolfram Language code: PersistentSymbol["e3"]

The default setting for ExpirationDate is to never expire:

Wolfram Language code: PersistentSymbol["Eternal"] = 42;
Wolfram Language code: PersistentObject["Eternal", $PersistenceBase]["ExpirationDate"]

Properties & Relations  (1)

Values specified with PersistenceTime are converted to absolute expiration dates:

Wolfram Language code: PersistentSymbol["x", "KernelSession", PersistenceTime -> 5] = 1;
Wolfram Language code: PersistentObject["x", "KernelSession"]["ExpirationDate"]
Wolfram Research (2017), ExpirationDate, Wolfram Language function, https://reference.wolfram.com/language/ref/ExpirationDate.html.

Text

Wolfram Research (2017), ExpirationDate, Wolfram Language function, https://reference.wolfram.com/language/ref/ExpirationDate.html.

CMS

Wolfram Language. 2017. "ExpirationDate." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/ExpirationDate.html.

APA

Wolfram Language. (2017). ExpirationDate. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ExpirationDate.html

BibTeX

@misc{reference.wolfram_2026_expirationdate, author="Wolfram Research", title="{ExpirationDate}", year="2017", howpublished="\url{https://reference.wolfram.com/language/ref/ExpirationDate.html}", note=[Accessed: 12-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_expirationdate, organization={Wolfram Research}, title={ExpirationDate}, year={2017}, url={https://reference.wolfram.com/language/ref/ExpirationDate.html}, note=[Accessed: 12-June-2026]}