Attributes

Attributes[symbol]
gives the list of attributes for a symbol.

DetailsDetails

  • The attributes of a symbol can be set by assigning a value to Attributes[s]. If a single attribute is assigned, it need not be in a list.
  • Attributes[s]={} clears all attributes of a symbol.
  • Attributes[{s1, s2, ...}] gives a list of the attributes for each of the .
  • Attributes["string"] gives the attributes for Symbol["string"].
  • Attributes[HoldPattern[s]] is treated as equivalent to Attributes[s].
  • Attributes for functions must be set before any definitions that involve the functions are given.
  • The complete list of possible attributes for a symbol f is:
  • Constantall derivatives of f are zero
    Flatf is associative
    HoldAllall the arguments of f are not evaluated
    HoldAllCompletethe arguments of f are completely shielded from evaluation
    HoldFirstthe first argument of f is not evaluated
    HoldRestall but the first argument of f are not evaluated
    Listablef is automatically "threaded" over lists
    Lockedattributes of f cannot be changed
    NHoldAllthe arguments of f are not affected by N
    NHoldFirstthe first argument of f is not affected by N
    NHoldRestall but the first argument of f are not affected by N
    NumericFunctionthe value of f is assumed to be a number when its arguments are numbers
    OneIdentity, , etc. are equivalent to a in pattern matching
    Orderlessf is commutative
    Protectedvalues of f cannot be changed
    ReadProtectedvalues of f cannot be read
    SequenceHoldSequence objects in the arguments of f are not flattened out
    StubNeeds is automatically called if the symbol is ever input
    Temporaryf is a local variable, removed when no longer used
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