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HandlerFunctions

is an option that specifies functions to apply when events are generated.

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HandlerFunctions

HandlerFunctions

is an option that specifies functions to apply when events are generated.

Details

  • The typical setting for HandlerFunctions is "event1"->f1,"event2"->f2,…, which specifies that when eventi is generated, the function fi should be applied to an association whose elements are specified by HandlerFunctionsKeys.
  • The events that can be generated by particular tasks are listed under the functions that submit the tasks.
  • In the HandlerFunctions association, the special element "UnhandledEvent"->f uses the function f for any event for which no explicit handler was specified.

Examples

Basic Examples  (8)

Display the result of evaluation after the task is finished:

Wolfram Language code: SessionSubmit[Integrate[Log[t] ^ 4 / Sqrt[1 - t ^ 2], {t, 0, 1}], HandlerFunctions -> <|"TaskFinished" :> MessageDialog|>, HandlerFunctionsKeys -> {"EvaluationResult"}]

Print the complete Association available to a handler function:

Wolfram Language code: SessionSubmit[N[Pi, 200], HandlerFunctions -> <|"TaskFinished" -> Print|>, HandlerFunctionsKeys -> All]

Display the result of Print evaluated in a subkernel:

Wolfram Language code: LocalSubmit[Print["Hello!"], HandlerFunctions -> <|"PrintOutputGenerated" -> (Print[#PrintOutput]&)|>, HandlerFunctionsKeys -> {"EvaluationExpression", "PrintOutput"}]

Display a dialog when a message is generated:

Wolfram Language code: SessionSubmit[1 / 0, HandlerFunctions -> <|"MessageGenerated" -> MessageDialog|>, HandlerFunctionsKeys -> {"EvaluationExpression", "MessageOutput"}]

Print messages generated by the subkernel:

Wolfram Language code: LocalSubmit[1 / 0, HandlerFunctions -> <|"MessageGenerated" -> (Message[#MessageOutput]&)|>, HandlerFunctionsKeys -> {"MessageOutput"}]

Handle the "BodyReceived" event when it is generated by URLSubmit:

Wolfram Language code: URLSubmit["http://www.wolfram.com", HandlerFunctions -> <|"BodyReceived" -> Print|>]

Store the headers with a variable when they are received:

Wolfram Language code: URLSubmit["http://www.wolfram.com", HandlerFunctions -> <|"HeadersReceived" -> ((headers = #Headers)&)|>]
Wolfram Language code: headers

Print the status code and content type when the task is finished:

Wolfram Language code: URLSubmit["http://www.wolfram.com", HandlerFunctions -> <|"TaskFinished" -> Print|>, HandlerFunctionsKeys -> {"StatusCode", "ContentType"}]
Wolfram Research (2016), HandlerFunctions, Wolfram Language function, https://reference.wolfram.com/language/ref/HandlerFunctions.html.

Text

Wolfram Research (2016), HandlerFunctions, Wolfram Language function, https://reference.wolfram.com/language/ref/HandlerFunctions.html.

CMS

Wolfram Language. 2016. "HandlerFunctions." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/HandlerFunctions.html.

APA

Wolfram Language. (2016). HandlerFunctions. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/HandlerFunctions.html

BibTeX

@misc{reference.wolfram_2026_handlerfunctions, author="Wolfram Research", title="{HandlerFunctions}", year="2016", howpublished="\url{https://reference.wolfram.com/language/ref/HandlerFunctions.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_handlerfunctions, organization={Wolfram Research}, title={HandlerFunctions}, year={2016}, url={https://reference.wolfram.com/language/ref/HandlerFunctions.html}, note=[Accessed: 13-June-2026]}