Can you use "conditionals" with variables?

brian_brady

What I mean here is can you do things like; if x>10 then y=0.5*x else y=x. What about logical functions like AND and OR? If conditionals and logicals could be used, then I could easily "program" multiple variables to change off one or two primary parameters. For example, enter a woodruff key number (i.e. 204) into a variable and use conditional logic to set all of the dimensions. Diameter and thickness can be done without conditionals, but the offset cannot, it varies from size to size.

On the other hand, can FS be used to just import existing variables and set values to new variables that can be used in a part model without actually making any geometry?

ilya_baran

Yes and yes.  The syntax for your conditional expression is:

#x > 10 ? 0.5 * #x : #x<br>

Another possibility (without using a custom feature) is something like:

{ 202 : 0.248 in, 204 : 0.491 in, 305 : 0.612 in}[#keyNumber]<br>

which if #keyNumberis 202 will evaluate to 0.248 in, etc (what this expression does is define a map from key to length and then does a lookup in this map).

Finally, if you need fancier logic, you can get and set variables in a custom feature.

ilya_baran

Yes and yes.  The syntax for your conditional expression is:

#x > 10 ? 0.5 * #x : #x<br>

Another possibility (without using a custom feature) is something like:

{ 202 : 0.248 in, 204 : 0.491 in, 305 : 0.612 in}[#keyNumber]<br>

which if #keyNumberis 202 will evaluate to 0.248 in, etc (what this expression does is define a map from key to length and then does a lookup in this map).

Finally, if you need fancier logic, you can get and set variables in a custom feature.

brian_brady

Great. Thanks for the answer. Can AND and OR be used, maybe as && and ||?

ilya_baran

Yes -- exactly && and ||.

jonathan_monette

Is there a list of these logical variable control that I could refer to? Or documentation's?

MBartlett21

@jonathan_monette
These are just standard javascript constructs

ilya_baran

These are not JavaScript but FeatureScript -- there's some syntax similarity, but it's unrelated otherwise.  Documentation "for mechanical engineers" is here: https://cad.onshape.com/help/Content/numeric-fields.htm?Highlight=expressions but is incomplete.  A more complete description is in the FeatureScript documentation: https://cad.onshape.com/FsDoc/syntax.html#expression-types

Note that what you enter into the expression fields is not quite FeatureScript syntax.  The main differences are that shorthand units (eg., "in" rather than "inch") are allowed, the multiplication before a unit is optional in some cases (as in "3 inch" rather than "3 * inch"), #foo for accessing context variable foo, and a couple of other minor differences.