Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

What causes variable editor to be blank for OOP (openvar)

Asked by Dan K on 6 Nov 2012

Hi,

I've got some fairly large OOP classes defined (which are subclasses of another). Sometime recently, I must have changed something, because now the variable editor/viewer ('openvar') shows blank when I try to open an object of one of these classes (even if I return just the default state of the object. i.e. X = myObj();)

What are the conditions that can cause this? I'm not getting any errors in the constructors, so I don't know where to start looking.

Thanks, Dan

Please does anybody know anything about this? I don't have any idea how to find the part of the code that is responsible. Thanks. Dan

2 Comments

per isakson on 6 Nov 2012

Just typing "X" at the command prompt, does that show any property values?

>> X
X = 
  class_handle handle
    Properties:
      a: 0
      b: 0
Dan K on 7 Nov 2012

To answer your question: The class has an overloaded disp method, and it correctly presents that output. properties(X) gives a correct list of the properties. When I include the following lines at the beginning of the overloaded disp:

builtin('disp',obj);

return

It does provide a correct listing in the format that you specify.

V/r,

Dan

Dan K

Products

2 Answers

Answer by Dan K on 6 Feb 2013
Accepted answer

Update for anybody who may care... I opened a support case to get some help from TMW on this... While waiting I discovered that the culprit was a faulty line of code in a get method for a dependent variable. I don't know that this is the only possible cause of this symptom, but hopefully it gives somebody else a place to start looking.

Dan

0 Comments

Dan K
Answer by Daniel on 7 Nov 2012

This has come up a number of times on Answers. I am pretty sure the variable editor cannot handle custom classes. I would start with this question to see the history. Yair has "customizing the Variable (Array) Editor" on his blog's todo list. My guess is it involves a lot of undocumented java. A donation to his blog might move it up the list....

1 Comment

Dan K on 7 Nov 2012

Daniel,

Thank you for the response. I can vouch that the variable editor can handle custom classes as a closely related class which I've constructed shows up just fine. What I find particularly perplexing is that it isn't showing null properties, but isn't even listing the properties.

V/r, Dan

Daniel

Contact us