Re: removing rules from function definitions

*To*: mathgroup at smc.vnet.net*Subject*: [mg33036] Re: removing rules from function definitions*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 27 Feb 2002 00:47:51 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <a5fm7i$e1k$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, we have had the problem three weeks ago and DownValues[f] = DownValues[f] /. (Verbatim[HoldPattern][f[i_Integer]] :> _) /; i > 1 :> Sequence[] will do that. Regards Jens Erich Neuwirth wrote: > > let me explain my problem with a simplified example > i define > f[1] := f[1] = 1 > f[n_] /; n > 1 := f[n] = f[n - 1]*2 > after evaluating f[1] > i have > > In[36]:= > FullForm[DownValues[f]] > > Out[36]//FullForm= > List[RuleDelayed[HoldPattern[f[1]],1],RuleDelayed[HoldPattern[f[2]],2], > RuleDelayed[HoldPattern[f[3]],4],RuleDelayed[HoldPattern[f[4]],8], > RuleDelayed[HoldPattern[f[5]],16],RuleDelayed[HoldPattern[f[6]],32], > RuleDelayed[HoldPattern[f[7]],64],RuleDelayed[HoldPattern[f[8]],128], > RuleDelayed[HoldPattern[f[9]],256], > RuleDelayed[HoldPattern[f[10]],Times[f[Plus[10,-1]],2]], > > RuleDelayed[HoldPattern[Condition[f[Pattern[n,Blank[]]],Greater[n,1]]], > Set[f[n],Times[f[Plus[n,-1]],2]]]] > > no i want to remove all the rules which were added during the > evaluation. > Drop[DownValues[f],MyPattern] > essentially allows me to create a new rules list, > but i cannot get MyPattern right > > MatchQ[#,RuleDelayed[HoldPattern[f[_Integer],_Integer]] > > does not work because HoldPattern gets evaluated, > but doing it Verbatim does not work either > because then _Integer is not evakuated and therefore does not work any > more. > > i really ned a pattern matching all rules > > RuleDelayed[HoldPattern[f[_Integer]],_Integer] > > which interprets _Integer nonverbatim, but everything else verbatim. > can anybody help me? > > -- > Erich Neuwirth, Computer Supported Didactics Working Group > Visit our SunSITE at http://sunsite.univie.ac.at > Phone: +43-1-4277-38624 Fax: +43-1-4277-9386