Sannyasin, It works with any text. Outside of listboxes I let users write formulas for things like pricing and commissions. It's nice to let them do this in terms of things they understand so a formula can look like:
P= (Cost * x) + Z P= (MSRP * (1 - x)) + Z There are two ways you can evaluate them. Native 4D code: You need to have a a process var defined for the result, I use: 'pfcr_price'. Here's a simplified version of a method used to calculate selling prices. $1 would be a formula like the ones above. x and Z are most likely static and the cost and msrp vary depending on the item. $formula:=$1 $x:=$2 $z:=$3 $cost:=$4 $MSRP:=$5 $exe_string:=Price_formula_insert_values ($formula;$x;$z;$MSRP;$cost) $exe_string:=Replace string($exe_string;",";"") $exe_string:=Replace string($exe_string;"P=";"pfcr_price:=") EXECUTE FORMULA($exe_string) $0:= pfcr_price Price_formula_insert_values handles inserting the actual values for the 4 variables, x, z, cost and msrp. Then I remove any commas (in v15 they started choking execution) and swap "P=" for the name of my variable. Now just execute the line and return the result. NTK from Rob Laveaux Since acquiring NTK I've started using Rob's execute function. Preparation is the same but it works in a single call. Plus he let's you tokenize the formula which is good if you will be applying it to large data sets. Another cool tidbit in NTK. You have to be careful here about how sophisticated you want to get. You could let users reference any 4D math functions, for example. But you will need to do the error checking for things like unclosed parens and such. I keep things pretty simple for the most part. And like I say to provide on-the-fly ability to do something like add a string of numbers or enter an amount with a 3.25% discount in a single line is pretty cool. If you have really sophisticated users you can provide an formula window on a form, or a listbox line, and give them access to any variables you have defined. Speed becomes an issue if you start looking at thousands of operations but for the flexibility the trade off can be worth it. Or you can look into NTK as I mentioned. On Sun, Sep 24, 2017 at 12:04 PM, Sannyasin Siddhanathaswami via 4D_Tech < 4d_tech@lists.4d.com> wrote: > Very cool idea! Does this formula evaluation only work with arrays? Or > text fields too? > -- Kirk Brooks San Francisco, CA ======================= *The only thing necessary for the triumph of evil is for good men to do nothing.* *- Edmund Burke* ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **********************************************************************
