Re: Preprocessing file input
- To: mathgroup at smc.vnet.net
- Subject: [mg121283] Re: Preprocessing file input
- From: David Bailey <dave at removedbailey.co.uk>
- Date: Wed, 7 Sep 2011 05:40:36 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <j44jkp$8s3$1@smc.vnet.net>
On 06/09/2011 08:55, Wolfgang Windsteiger wrote: > Hi everyone, > > is there some hook for preprocessing expressions when they are read from > a file. I'm looking for an analogon to $Pre, which applies to each > expression read from a file. E.g. I have file.m containing > > expr1 > expr2 > expr3 > > and when I do > > <<file.m > > what I would like to happen is > > $PreFile[expr1] > $PreFile[expr1] > $PreFile[expr1] > > Is there something like $PreFile??? > > Thanks for any suggestion, > WW. > Not exactly, but if you open the file as an input stream with OpenRead, you can read expressions using: Read[strm,Hold[Expression]] The expressions are returned unevaluated, wrapped in Hold, so you can apply whatever function you want at that point. David Bailey http://www.dbaileyconsultancy.co.uk