Meaning of less/greater than in handle objects

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Daniel Dolan 2020-9-17

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评论： Daniel Dolan 2020-9-17

What is the meaning of less/greater than in handle objects? Here is a simple example.

classdef SimpleHandle < handle
    
end

When I create and compare two objects:

a=SimpleHandle();
b=SimpleHandle();
a > b

the result is randomly true or false.

I understand the use of == versus isqual for handle objects, but the notion of greater/less than eludes me.

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Answer 1

Bruno Luong 2020-9-17

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I believe the graphic handle object at one point of MATLAB history (before R2014b?) is just a double numbers unique assigned too each object.

They are used to identify the object. Matlab later replace HANDLE with a real object, but keep comparison for compatibility.

Shouldn't worry about comparing them, it's meaningless operation.

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Walter Roberson 2020-9-17

You can still double() any handle, and handle() any double (but the result might be an invalid handle.)

Daniel Dolan 2020-9-17

Numeric representations of graphic handles are still available, so I can see why inequality methods might have been implemented. There must be some kind of number associated with every object, but double(obj) only works for graphic handles, not direct subclasses of handles.

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