Re: ReplaceAll question

*To*: mathgroup at smc.vnet.net*Subject*: [mg82562] Re: ReplaceAll question*From*: Albert <awnl at arcor.net>*Date*: Wed, 24 Oct 2007 04:37:02 -0400 (EDT)*References*: <ffkf46$sh6$1@smc.vnet.net>

Yaroslav Bulatov wrote: > b = 3; > Hold[a[[b]]] /. {b -> c} > > ReplaceAll has no effect, why? Because the rule b -> c is evaluated to 3 -> c before it is applied, and the latter doesn't match anything, which at least is better than to match something that shouldn't... > What is the recommended way of carrying > out the replacement above? Hold[a[[b]]] /. {HoldPattern[b] -> c} hth, albert