Where is the 'up' property/function defined for biograph nodes/edges?

Using biograph library, nodes and edges have a property or function called 'up' that is used all over the library, looks like I have to use 'up' in order to implement the new functionality I am trying to add. I think it simply returns the graph that the node/edge object belongs to, but I am not sure. Where is this 'up' property or function defined?

For instance, this code uses this 'up' property/function.

cm = [0 1 1 0 0;1 0 0 1 1;1 0 0 0 0;0 0 0 0 1;1 0 1 0 0];
bg = biograph(cm);
upbg = bg.Nodes(1).up

This returns

Biograph object with 5 nodes and 9 edges.

Problem is, I can't find a property or function called 'up' anywhere. I can't find it in the documentation, it is not defined in the @node/scheme.m file, and there is no @node/up.m function, calls to "get(bg.Nodes(1))" does not show any 'up' property, in the debugger it steps over any line of code referring to 'up' as if it were a property, and I can't seem to find any place in the code where an 'up' property variable is actually set on any node or edge, the inspector window does not list this attribute.

What is this edge/node 'up' property or method, where is it defined?

Answer 1

[Corey]

I think I figured it out. I think 'up' parameter points to the parent biograph object for all nodes/edges in a biograph. I believe it is defined and set in the constructor. For instance, in @biograph/@node/node.m:

connect(h,hPar,'up')

I don't know where the connect() function is defined though, so I don't know what else it does.

Answer 2

[Walter Roberson]

Hidden property? http://www.mathworks.com/help/matlab/matlab_oop/property-attributes.html; see http://undocumentedmatlab.com/blog/displaying-hidden-handle-properties

Hidden method? http://www.mathworks.com/help/matlab/matlab_oop/method-attributes.html. I am not sure but I think the above undocumentedmatlab link might help for that.

Private property? see http://undocumentedmatlab.com/blog/accessing-private-object-properties

[Corey]

Very helpful, thanks!