Defer

Defer[expr]

yields an object that displays as the unevaluated form of expr, but that is evaluated if it is explicitly given as Wolfram Language input.

Details

  • Defer[expr] returns an object that remains unchanged until it is explicitly supplied as Wolfram Language input and evaluated using TemplateBox[{shift, return}, Key1, BaseStyle -> {Notes, FontWeight -> Plain, FontFamily -> Source Sans Pro}], Evaluate in Place, etc.
  • Defer gives an object whose evaluation is merely deferred until it is explicitly given as Wolfram Language input; HoldForm gives an object that is never evaluated.
  • If an object contains several levels of nested Defer constructs, one level is removed each time the object is evaluated as Wolfram Language input.
  • Defer prevents evaluation, not formatting. Objects such as Grid and Manipulate will still format in StandardForm in the usual way when wrapped in Defer.

Examples

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Basic Examples  (2)

By default, arguments are evaluated:

Use Defer to display an unevaluated form:

Copy the previous output and evaluate:

Use Defer to create cells with unevaluated contents:

Properties & Relations  (1)

Use HoldForm to display in unevaluated form:

Copy the output and evaluate; the result stays unevaluated:

Use ReleaseHold to force evaluation of the result:

Use Defer to display in unevaluated form:

Copy the output and evaluate:

Possible Issues  (1)

Defer prevents evaluation, not typesetting:

Use InputForm or ToString to prevent typesetting:

Wolfram Research (2007), Defer, Wolfram Language function, https://reference.wolfram.com/language/ref/Defer.html.

Text

Wolfram Research (2007), Defer, Wolfram Language function, https://reference.wolfram.com/language/ref/Defer.html.

BibTeX

@misc{reference.wolfram_2020_defer, author="Wolfram Research", title="{Defer}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/Defer.html}", note=[Accessed: 15-April-2021 ]}

BibLaTeX

@online{reference.wolfram_2020_defer, organization={Wolfram Research}, title={Defer}, year={2007}, url={https://reference.wolfram.com/language/ref/Defer.html}, note=[Accessed: 15-April-2021 ]}

CMS

Wolfram Language. 2007. "Defer." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Defer.html.

APA

Wolfram Language. (2007). Defer. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Defer.html