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*: <cud7du$2u7$1@smc.vnet.net> <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 Global`F _F := _Integer but doesn't work: := _F // FullForm Blank[F] 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? Joe -- 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. =================

**References**:**Re: Mathematica to TeX***From:*Nasser Abbasi <nma@12000.org>