Re: Defining a function P[A_ | B_]:=f[A,B] overriding Alternatives
- To: mathgroup at smc.vnet.net
- Subject: [mg19287] Re: Defining a function P[A_ | B_]:=f[A,B] overriding Alternatives
- From: Eckhard Hennig <hennig at itwm.uni-kl.de>
- Date: Sat, 14 Aug 1999 01:45:13 -0400
- Organization: ITWM
- References: <7oojvg$i35@smc.vnet.net> <7or3jp$o6@smc.vnet.net> <7ouvht$osf$1@dragonfly.wolfram.com>
- Sender: owner-wri-mathgroup at wolfram.com
Allan Hayes schrieb in Nachricht <7ouvht$osf$1 at dragonfly.wolfram.com>...
>Eckhard:
>Following your idea n the posting below:
>
>p[HoldPattern[Alternatives][A_ , B_]] := {A, B}
>
>DownValues[p]
>
>{HoldPattern[p[HoldPattern[Alternatives][A_, B_]]] :> {A, B}}
>
>p[a | b]
>
>{a, b}
>
>Allan
Of course, that's the straightforward way to do this. However, the
originator of this thread (Peltio) wrote the following:
>And yet I wanted to be able to define my function without showing the
>Alternatives /: part.
Therefore, I suppose that Peltio's intention was to be able to define p[A_ |
B_] without any explicit manipulation of the behavior of Alternatives. This
can only be achieved by rewriting the DownValues of p.
-- Eckhard
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Dipl.-Ing. Eckhard Hennig mailto:hennig at itwm.uni-kl.de
Institut fuer Techno- und Wirtschaftsmathematik e.V. (ITWM)
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