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:

In[1]:=
Click for copyable input
Out[1]=

Use Defer to display an unevaluated form:

In[2]:=
Click for copyable input
Out[2]=

Copy the previous output and evaluate:

In[3]:=
Click for copyable input
Out[3]=

Use Defer to create cells with unevaluated contents:

In[1]:=
Click for copyable input
In[2]:=
Click for copyable input
In[3]:=
Click for copyable input
In[4]:=
Click for copyable input
In[5]:=
Click for copyable input
In[6]:=
Click for copyable input

Properties & Relations  (1)

Possible Issues  (1)

Introduced in 2007
(6.0)