Storing empty array in Attribute Dictionaries


So I’m setting my window array initially to an empty array @Windowlist = [] and then storing it as an attribute. When I save the file and then restart SketchUp and re-open the file I notice that the empty array is now “nil” and for some reason I can’t seem to set the variable back to an empty array, very strange behaviour.


Yes, this is a bug. The strange thing (if I remember correctly) is that the empty Array can still be fetched within the same SU session as it was set. I struggled with this for eitehr my railroad system or townhouse system some years back. I think I worked around it by adding || [] after the method reading the attribute, or by passing empty array as default value to attribute_read.


Of what class are the object item references in the @Windowlist array ?


I’m not even sure how to answer that question.

When the array is filled it looks something like this: [“window1”, “window2”, “window3”]


So it is just an array of window caption strings ?


Yes, just simple text entries so that I can keep track of the number of windows in a wall panel and also have a name to associate with a nested group.


I hate to hijack my own thread but a related problem I am trying to figure out in Ruby is how to easily sort an array of values from lowest to highest (numeric value) and also create a list of the keys in sorted order that reference these numeric values in a separate hash. I’m probably not explaining this one right.

Sorting arrays

Ah okay. I was thinking display window like dialog window, not “window” window.

A workaround might be to save your attribute as JSON text.

ary_str = [].to_json
# write ary_str to dictionary
# read it back into an array ...
a = JSON.parse(ary_str)


If my array is empty I just don’t attempt to store it as an attribute that seems to have avoided the issue all together. What a pain in the butt though, it had me pulling my hair out trying to figure out why the whole environment was getting unstable and why the problem only surfaced if I saved and the restarted SketchUp.


Some attribute oddities go away if you wrap the value into an object literal/hash. I don’t know if it might help here.


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