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internal details of Options, Default, Attributes

  • To: mathgroup at
  • Subject: [mg96374] internal details of Options, Default, Attributes
  • From: obott0 at
  • Date: Thu, 12 Feb 2009 06:39:36 -0500 (EST)

Are DefaultValues of variables basically like UpValues but restricted
to the Default and Options functions?

In[1]:= DefaultValues[LinearSolve]
Out[1]= {HoldPattern[Options[LinearSolve]] :> {Method -> Automatic,
Modulus -> 0, ZeroTest -> Automatic}}

If this is how it works, does Attributes work in the same way? In
other words, is there some function I can call with Plus that will
return something like:

In[1]:= SomeFunction[Plus]
Out[1]= {HoldPattern[Attributes[Plus]] :> {Flat, Listable,
NumericFunction, OneIdentity, Orderless, Protected}}

I tried setting an upvalue for a built-in function with Options, but
noticed that it only changed the DefaultValues of the function:

Options[LinearSolve] ^= {Method -> Automatic, Modulus -> 3, ZeroTest -
> Automatic}
(* this did not set an upvalue for LinearSolve *)

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