ClearAttributes

Turns off one of the Wolfram-named properties Attributes can report.

✓ checked against that system · ! checked, with disagreements (hover a chip)Wolfram LanguageClearAttributes!↗

ClearAttributes(f, attr)Turns $attr$ off for $f$'s operator definition, in place.

ClearAttributes(f, {attr1, attr2, ...})Turns off several attributes at once.

Typed signatures

Type	Package	Applies
(symbol, any) -> any	combinatorics	always

Domain: Collections

Details

• The inverse of SetAttributes, over the same $\{Flat, HoldAll, Listable, Orderless\}$. Declines (stays unevaluated) for an undeclared $f$ or any other attribute name.
• A declared head is Protected: ClearAttributes leaves the call unevaluated and says ClearAttributes::write (Tag f in f is Protected.), where Wolfram, whose Protected guards definitions rather than attributes, makes the change.
• Always returns $Nothing$, like Wolfram's own $Null$.

Examples

Basic #

turn Flat and Orderless on for a head of your own, clear Flat, then read the rest back

live ↗

In$\mathrm{Last}(\bigl\lbrack\mathrm{userHead}(x)\coloneq x, \mathrm{SetAttributes}(\mathrm{userHead}, \bigl\lbrack\mathrm{Flat}, \mathrm{Orderless}\bigr\rbrack), \mathrm{ClearAttributes}(\mathrm{userHead}, \mathrm{Flat}), \mathrm{Attributes}(\mathrm{userHead})\bigr\rbrack)$Out$\bigl\lbrack\mathrm{Orderless}\bigr\rbrack$

Wolfram needs no definition before a symbol takes attributes; here the head is defined first, since ClearAttributes leaves an undeclared symbol alone.

a declared head is Protected: the call stays unevaluated and says ClearAttributes::write

live ↗

In$\mathrm{ClearAttributes}(\mathrm{HarmonicMean}, \mathrm{Orderless})$Out$\mathrm{ClearAttributes}(\mathrm{HarmonicMean}, \mathrm{Orderless})$

About

Examples	2
Checked against	Wolfram Language 1 differ
Crosswalk	Wolfram Language

See also: Attributes, SetAttributes