expressions of type 'list'

[icetea73]

The expression editor allows to create expressions of type 'list'. The documentation mentions that list-expressions are used to "...streamline NX DesignLogic interactions and provide additional functionality capable of handling a wider variety of design tasks."

Intriguing! Can anybody comment on how to actually use list expressions? Can't figure it out and it sounds so useful...

 

[JohnRBaker]

OK, attached in one of my 'demo' parts (which was created and saved in NX 8.0) where I'm using the 'List' expressions as a sort of 'flat-database' where I have the parameters stored for all the parametric values for the features of various sized 'Handwheels'. When You open the part file, go to...

File -> Properties -> Attributes

...and look for the attribute named 'Handwheel_Size'. You will be able to change this attribute to any of the standard catalog sizes that are available as well as an option to have an add-on 'Handle' or not (just select 'True' or 'False' for the attribute named 'Handle'). I pass the value of 'Handwheel_Size' to the expression system where it's used to determine which set of values to read from the various 'lists' using the 'nth' function and then applying those values to the feature parameters of the model.

Anyway, take a look as this should help you see at least one example of how to use the 'List' Expression.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[JohnRBaker]

For another example of the use of the 'list' expression, see my last post in the thread:

http://www.eng-tips.com/viewthread.cfm?qid=364251

In this case I used a NESTED 'list' expression as sort of 'truth table' to control which features are suppressed and which ones are not.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[aluminum2]

Thanks for asking the question, I was wondering the same thing. Not to hijack the post, but do the expressions follow a known language or format?

 

[JohnRBaker]

Expressions have been around so long, since the days of UG Concept (UG V8.0, circa 1991), that we had only limited examples to go by, basically things like FORTRAN, COBAL, etc, as well as of course GRIP, which had it's own origins in the languages of its day, again things like FORTRAN, COBAL, SNOBOL as well as APT for geometry constructors. That beign said, the general syntax of an expression and it's use of operators and precedence, I think you will find pretty much matches the rules used for FORTRAN. Over the years we've added some more modern concepts such as 'Conditional IF statements' in addition to the original 'Arithmetic IF statemnts' but as you would expect, the basics have remained the same if for no other reason than to maintain upward compatibility when moving legacy models, at least since NX 8.0, to newer versions of UG/NX.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PSI-CAD]

Hi John

How did you create an attribute with a pull down choice ?

Thanks in advance

Regards
Didier Psaltopoulos

http://www.psi-cad.com

 

[icetea73]

Thanks John! I did not yet look into the examples but I will as soon as I have some spare time!

 

[JohnRBaker]

Go to the thread below...

http://www.eng-tips.com/viewthread.cfm?qid=364251

...scroll down to my May 5th posting at 10:53 and you'll find a description of how to set-up these sorts of Attributes. Just remember that these 'multiple choice' attributes can be either 'strings', 'floating point numbers', 'integers' etc.

Anyway, there should be enough information there for you to get started.


John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PSI-CAD]

Thanks a lot John

Regards
Didier Psaltopoulos

http://www.psi-cad.com