MATLAB: Remove completely an object inside another object

oop remove object

The property PipeBolt of the oject Bolt has several objects inside.

I can add new objects doing:

Bolt(1,1).PipeBolt(N,1) = newobj;

I can also delete an object doing:

Bolt(1,1).PipeBolt(N,1).delete

However the size of the Bolt(1,1).PipeBolt(N,1) will be the same before and after delete the object. I need to remove completely the object how can I do this?

Basically before I add a new object I have the size (3×1) but after delete the object I still have a 4×1 insted the original 3×1.

thank you in advance

Best Answer

You use the same rules to delete array elements regardless of their content, so:

Bolt(1, 1).PipeBolt(N, 1) = [];

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MATLAB: How can an object array be extented by itself

Hi,

interesting observation. I would explain as follows: the handle property means, that we use references to objects instead of the objects themselves. This means, that you can manipulate object properties without the need to return the changed object.

The structure of the object itself is not falling into this handle behavior. So you need to return the (new) object.

function obj = add(obj)
  N=length(obj)+1;
  obj(end+1,1)=TestAdd;
  obj(N,1).val=N;
end

Now you call as follows:

>> o = TestAdd(5)
  o = 
    5x1 TestAdd array with properties:
       val
>> o = o.add
  o = 
    6x1 TestAdd array with properties:
       val

Of course you can encapsulate this into a new class if you like :).

Hope this helps,

Titus

MATLAB: Error when Indexing and object + OOP

It likely depends what you are doing before that code. You would be best to pre-size your array of objects with e.g.

Bolt(1,1).PipeBolt = PipeLine.empty(N,0);

to ensure that the property is set to be of the type 'PipeLine', otherwise it will be a double by default, like all variables, so if you didn't explicitly instantiate it and then try to set e.g. its 7th element it will have created it as a double and be expecting a double to be given to it, not some other object type.

In general I initialise all my properties that are to be some other object as e.g.

myProp = SomeClass.empty;

or something like the example above if I expect it to be an array of objects. I cannot remember off the top of my head though - just doing the above and telling it the type of object without presizing may well be enough that your code causing an error would work because it knows the object type beforehand.

Best Answer

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MATLAB: How can an object array be extented by itself

MATLAB: Error when Indexing and object + OOP

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