Re: Mathematica 9: bug in merging cells

*To*: mathgroup at smc.vnet.net*Subject*: [mg128948] Re: Mathematica 9: bug in merging cells*From*: David Reiss <dbreiss at gmail.com>*Date*: Wed, 5 Dec 2012 03:13:18 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <k9kekh$68c$1@smc.vnet.net>

Just a quick observation to note that one does not need the comment between the first two code lines, the presence of a carriage return is all that's needed to create the error upon merging the two cells. Thus, the first cell would contain a = 1; b = 2; and the second cell would have any code in it: e.g., c = 3; Then merge the two and the error box appears. --David On Dec 4, 4:09 am, Fred Simons <f.h.sim... at tue.nl> wrote: > When writing a larger program, I usually test the single steps in > separate cells, then merge these cells and localize the variables by > wrapping the contents of the merged cells in a Module. By doing so in > Mathematica 9, due to a bug in merging cells, I lost a lot of code. I > reported this bug to WRI two weeks ago. It is not yet repaired in the > new release, so I thought I would mention this annoying bug here as well. > > This is an example (Mathematica 9 for Windows, I am not aware if this > happens for other systems too). > > Construct two input cells, the first one containing > > a=1; > (* comment *) > b=2; > > and the second one > > c=3; > > When merging these two cells the contents ending with the comment is > shown in an orange rectangle, with the error message that there is a > RowBox with an invalid first argument. I cannot see any reason why this > merging of cells could not be undone with ctrl-Z, but it cannot and > therefore part of my code was gone. > > In this simple example I could see how to fix it. Toggle ctrl-E for > seeing the box structure. Place a } just behind the RowBox with the > comment and a { behind the very first RowBox[, that is followed on the > next line with another RowBox. > > During writing this message, I found that the same happens when you try > to copy and paste the first cell. > > Fred Simons > Eindhoven University of Technology