What would be the best way to have an assert on a variable

brett_howard659

Is it possible to give a warning if I'm about to do something stupid with variables?

For example.  If I'm designing a block and I put in a line diameter of 12mm and I have a sheave width that is <12mm it would inform me that the sheave width must be greater than line diameter?  I mean I suppose I could model the rope and it would visually become obvious but it seems like something simpler would be more effective?

brett_howard659

I wasn't able to view the document you linked but I think I found similar information at this link (https://www.onshape.com/en/resource-center/tech-tips/tech-tip-how-to-use-expressions-for-numeric-fields-in-onshape)...  And this is very close and it is what I'm going to do for now...  Where I can do something like #sheaveDiameter = #lineDiamter + 1mm.  But what I'd prefer is the ability to set the minimum to be that value and anything larger is also allowed.

Actually I think I'm there now...

#sheaveWidth = 5mm
#lineDiameter = 6mm
#finalSheaveWidth = max(#lineDiameter+1mm,#sheaveWidth)

This way if they put in a width too narrow for their intended line it bumps them to 1mm bigger than the line.  But if they want the sheave wider they can put that in and that request gets honored too.  I think that is about as nice as I can get things.  

Thank you all for the ideas!

MichaelPascoe

The max function works in this case. If you ever need more detailed statements instead of a simple function, ternary conditional operators are the way to go. So in the statement below, if the modified line diameter is greater than the sheaveWidth, return the modified diameter; else, return the sheaveWidth. 

#finalSheaveWidth = (#lineDiameter+1mm) > #sheaveWidth? #lineDiameter+1mm : #sheaveWidth

See this post to get started Ternary Conditional Operators (Quick Guide)
And here are the official help tutorials in the learning center Variables and Expressions Course

NeilCooke

Configuration variables have limits

brett_howard659

Hrm...  I'll read more about configuration vars...  If the limits can be a function of another var that sounds like exactly what I'm looking for. 

eric_pesty

brett_howard659 said:

Hrm...  I'll read more about configuration vars...  If the limits can be a function of another var that sounds like exactly what I'm looking for. 

Unfortunately the limits are not "adjustable" based on other inputs (at least last time I checked...). There are a number of improvement requests related to adding "logic" to configurations (to control available options based on another input)

S1mon

It is possible to use expressions to do some funky logic.

https://learn.onshape.com/learn/course/variables-and-expressions/expressions/advanced-expressions?page=1

brett_howard659

I wasn't able to view the document you linked but I think I found similar information at this link (https://www.onshape.com/en/resource-center/tech-tips/tech-tip-how-to-use-expressions-for-numeric-fields-in-onshape)...  And this is very close and it is what I'm going to do for now...  Where I can do something like #sheaveDiameter = #lineDiamter + 1mm.  But what I'd prefer is the ability to set the minimum to be that value and anything larger is also allowed.

Actually I think I'm there now...

#sheaveWidth = 5mm
#lineDiameter = 6mm
#finalSheaveWidth = max(#lineDiameter+1mm,#sheaveWidth)

This way if they put in a width too narrow for their intended line it bumps them to 1mm bigger than the line.  But if they want the sheave wider they can put that in and that request gets honored too.  I think that is about as nice as I can get things.  

Thank you all for the ideas!

MichaelPascoe

The max function works in this case. If you ever need more detailed statements instead of a simple function, ternary conditional operators are the way to go. So in the statement below, if the modified line diameter is greater than the sheaveWidth, return the modified diameter; else, return the sheaveWidth. 

#finalSheaveWidth = (#lineDiameter+1mm) > #sheaveWidth? #lineDiameter+1mm : #sheaveWidth

See this post to get started Ternary Conditional Operators (Quick Guide)
And here are the official help tutorials in the learning center Variables and Expressions Course

brett_howard659

Oh rock on...  I'm totally used to ternary operators...  I'm an EE and Software guy by degrees so I'm slowly trying to learn this ME stuff too.  Thank you guys for all the pointers!