UpValues for Blank[foo]
- To: mathgroup at smc.vnet.net
- Subject: [mg54166] UpValues for Blank[foo]
- From: Josef Karthauser <joe at tao.org.uk>
- Date: Sat, 12 Feb 2005 01:57:23 -0500 (EST)
- References: <email@example.com> <200502110833.DAA09117@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
I wonder what's I'm doing wrong. I'm trying to change the upvalues of a
function with respect to Blank so as to have it dynamically changed
into something else, e.g.
:= F /: Blank[F] := _?FQ
where FQ[F] returns true, and false on anything else, but although
installed it doesn't appear to work.
To simplify the example I wondered whether I could define my own _F to
behave like _Integer, i.e.
:= F /: Blank[F] := Blank[Integer]
which appears to be in place as a rule:
:= ?? F
_F := _Integer
but doesn't work:
:= _F // FullForm
I thought that maybe wrapping HoldPattern around the Blank[F] in the
upvalue rule might have fixed it, but it doesn't.
Is there some special handling for Blank within mathematica? Can I
circumvent it somehow?
Josef Karthauser (joe at tao.org.uk) http://www.josef-k.net/
FreeBSD (cvs meister, admin and hacker) http://www.uk.FreeBSD.org/
Physics Particle Theory (student) http://www.pact.cpes.sussex.ac.uk/
================ An eclectic mix of fact and theory. =================
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