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

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Dan K 2012-11-6

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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

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per isakson 2012-11-6

在 MATLAB Online 中打开

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 2012-11-7

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

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Answer 1

Dan K 2013-2-6

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https://ww2.mathworks.cn/matlabcentral/answers/52964-what-causes-variable-editor-to-be-blank-for-oop-openvar#answer_74058

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

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Answer 2

Daniel Shub 2012-11-7

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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....

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Dan K 2012-11-7

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

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