Topic: Help with While loop

[jmcshane]

Hi,

This may sound fairly simple and I'm sure it is, but for some reason I can't seem to figure it out.
Can someone who has some time tell me why I get an error when trying to quit the loop below?

Code: [Select]

(while
     (setq obj (vlax-ename->vla-object (car (entsel))))
     (if (= (vla-get-ObjectName obj) "AcDbBlockReference")
       (vla-put-rotation
obj
(dtr (+ (rtd (vla-get-rotation obj)) 180))
       )
       (princ
"\nSelected Object was not a block!.......Please try again: "
       )
     )
  )

Whenever I hit enter it returns :

Code: [Select]

error: bad argument type: lentityp nil

Any guidance would be gratefully accepted.

John

[Lee Mac]

vlax-ename->vla-object will error when provided with nil, hence test for a nil entity selection (car (entsel)) before converting it to a vla-object

[jmcshane]

Thank you,
I had better go and look at all the rest of my routines that throw this error.

Many thanks


John

[ronjonp]

You could also take out the conversion from radians to degrees with something like this:

(+ pi (vla-get-rotation obj))

[jmcshane]

Mathamatics was never my strongest point, so I never knew that!
So that makes it two useful pieces of information I learned today.

Thanks.
John

[Lee Mac]

Gotta love mathematics 

This will be an interesting read for you

[jmcshane]

Ha Ha 

You guys even throw in a bit of personal development as well as the programming advice.
Back in the day....(way back now that I think of it) I used to work all this out with a pencil and a compass!
No need for maths (untill today!)

Thanks for the help.

John

[Spike Wilbury]

Gotta love mathematics 

This will be an interesting read for you

I loved my math and geometry classes a lot - got the opportunity to have these classes also in my university years (5 years)

[Lee Mac]

Gotta love mathematics 

This will be an interesting read for you

I loved my math and geometry classes a lot - got the opportunity to have these classes also in my university years (5 years)

Just curious, what degree did you study Luis?

[curmudgeon]

Gotta love mathematics 

This will be an interesting read for you

I am sometimes surprised with the usefulness of wikipedia. I had been interested in calculating a centroid from scratch with lisp, and to do that I used their algorithm to get the area in the process.

the unintended consequence you may appreciate, and I will share. if that method is employed for area, you can end up with a negative area. as I recall, a negative area implied the vertexes of the polygon had a clockwise rotation, a positive area counter clockwise.

[Spike Wilbury]

architecture

Gotta love mathematics 

This will be an interesting read for you

I loved my math and geometry classes a lot - got the opportunity to have these classes also in my university years (5 years)

Just curious, what degree did you study Luis?

[Lee Mac]

I see, cool 

architecture

Gotta love mathematics 

This will be an interesting read for you

I loved my math and geometry classes a lot - got the opportunity to have these classes also in my university years (5 years)

Just curious, what degree did you study Luis?