Example of FeatureScript functions in Variable features?

EvanReese

I'm looking at the help documentation for variables here and I see that custom functions can be written with Featurescript syntax inside of a Variable feature. I understand the example given, but I'm curious if anyone has any examples of a time they found this functionality particularly handy. It seems like a powerful capability, but I'm having a hard time imagining a use-case for myself. Does anyone have anything cool they want to show?

tim_hess427

That is cool! I didn't realize we could do that - thanks for pointing it out. 

I'm trying to think of examples, but anything I can come up with involving calculations could just as easily be done with a combination of variables and configurations. So, I would think this would be most valuable in situations where you want to avoid typing the same expression multiple times or if there are things you could do in a function that go beyond the simple calculations?  Would you be able to do queries or evaluations within these functions?

EvanReese

@tim_hess427
That's kind of where I'm stuck. I can't think of a function I'd run more than once or twice, in which case I may as well just type it as an equation, but the fact that it's there has me very curious about the scenarios where it's indispensable. There's got to be a few, right?

I can't say for sure, but I don't think queries or evals are possible in the functions.

konstantin_shiriazdanov

I think we have this capability because there is a kind of input field which accepts any valid featurescript expression (isAnything() predicate in featurescript). So that lambda or ternary operator can be used as soon as they all are valid language constructions, and it was for free and they didn't requare any additional efforts to provide functionality for exporting lambda's into context variables, but if they wanted to restrict some type of expression as input it would requare additional job so it's just win-win.

EvanReese

@konstantin_shiriazdanov
That makes sense. I guess I'm just really hoping there's some perfect application for it because that would excite me.

john_mcclary

 setVariable(context, "sm", function(x) {  return x  + 1; } );                  // Works
 setVariable(context, "sm-guage", function(x) {  return SM_Table[x].Size; } );  // doesn't work

It won't let me read from a map though

Otherwise it would be handy to make a toolkit FS that holds a bunch of common functions as vars.

for example, the pitch dia of a sprocket.
I always just type it out long form in the dimension, but there are only two parameters, chain pitch and tooth count.
so it would be cool to just type #Sprocket_Pitch_dia(.75,11)  and not have to remember if you need to multiply the pitch by sin() or divide.. (I get it wrong half the time)

setVariable(context, "Sprocket_Pitch_Dia", function(x,y) {  return x/sin(180*degree/y); } );

EvanReese

@john_mcclary
now, this is an interesting idea! I like the toolkit concept. If someone works with a particular system that has common equations, then a feature could be written to turn each equation into a function to make downstream calculations way faster and less error-prone.

Bummer that the map didn't work. Any ideas on a workaround?

john_mcclary

Oh, actually it does work with a map.

My issue was I had a "-" in the name, apparently that is not a valid  variable name. My bad

tim_hess427

@john_mcclary Are you defining the map in a separate featurescrip? 

Sorry if its a dumb question - I'm just starting to dig into featurescript. 

john_mcclary

Yea, In this case I do have a featurescript that is basically a custom bend table where it gives a bend radius and stock size by inputing the Guage of the material

But you could make your map in the same file if you want.

export const SM_Table =
{ 
    .25 : { Name : "1/4\" (.25)", Size : .25, Bend : .262 },
    7 : { Name : "7 Gauge  (.1793)", Size : .1793, Bend : .262 },
    10 : { Name : "10 Gauge (.1345)", Size : .1345, Bend : .164 },
    11 : { Name : "11 Gauge (.1196)", Size : .1196, Bend : .164 },
    12 : { Name : "12 Gauge (.1046)", Size : .1046, Bend : .164 },
    14 : { Name : "14 Gauge (.0747)", Size : .0747, Bend : .079 },
    16 : { Name : "16 Gauge (.0598)", Size : .0598, Bend : .079 },
    18 : { Name : "18 Gauge (.0478)", Size : .0478, Bend : .079 }