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based on an earlier version of the Wolfram Language.
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Evaluate

Evaluate[expr]
causes expr to be evaluated even if it appears as the argument of a function whose attributes specify that it should be held unevaluated.
  • Evaluate only overrides HoldFirst, etc. attributes when it appears directly as the head of the function argument that would otherwise be held. »
Evaluate inside a Hold:
Evaluate inside a Hold:
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Evaluate works for arguments of any symbol with attributes HoldAll, HoldFirst, or HoldRest:
Since Attributes is HoldAll, use Evaluate to find the properties of the value of x:
Unprotect a system symbol to make a definition for it:
Restore protection:
Force evaluation of the right-hand side of a delayed definition:
Build a function from an expression:
Evaluate does not work inside functions with attribute HoldAllComplete:
Use Unevaluated to temporarily treat a function as if it were HoldAll:
Evaluate does not work inside Unevaluated:
Evaluate works only on the first level, directly inside a held function:
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