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Set matlab1/11/2024 So I only have to perform order-independent comparison and don't need to waste performance on ensuring unrequired properties. In my use case, I don't even need the uniqueness property of sets. So, I can simply assign the fields in question like this and don't have to change anything else in my code: a = Set() % custom type Contrary to my previously stated belief, MATLAB actually does allow for class-specific overriding of isequal. I've found a way to solve my problem elegantly. Is there any datatype in MATLAB which allows for the described behavior? Or is there a way to easily build such a custom type? In Java, I could simply write a wrapper class with a custom implementation for the equals method, but there seems to be no such mechanism in MATLAB? Other than this ordering problem, the inbuilt isequal function covers all of my needs, as it correctly handles arbitrarily nested structs with arbitrary fields, so I would really like to avoid writing a complicated custom function for that. However, in my case the arrays are non-trivially nested inside the structs I am trying to compare via isequal, and it would be quite complicated to write a custom comparison function for the encapsulating structs. Another approach would be not to use isequal, but rather a custom comparison function which asserts matching lengths and then simply checks if each element from the first array is contained in the second one. Unfortunately, in my case the elements are complex objects which cannot easily be mapped to have an unambigious numerical relationship to each other. The easy fix would be to sort the entries before comparing them. Basically, what I want is an array, but without imposing an order on the contained elements. Otherwise, the above explanation & official matlab docs is doing the job for value class getter/setters.I am looking for a way to compare finite sequential data with non-deterministic ordering in MATLAB. myclassinstance.MyProp will work without any just as well.įinally, getters/setters for value classes are something that in my 7 years of matlab oop, so my advise would be to go with handle classes and enjoy happy matlab coding :-) Of course it goes without saying that you dont need to define a getter if you just want to return the value, i.e. Now, regarding setters/getters: for handle classes, everything feels java-ish now: classdef M圜lass < handleįunction set.MyProp(this, value) %Note: setMyProp is also valid! this is more native to matlab-style, but somehow makes it harder to see you're calling an objects method. Mind you, this is the java-perspective (and also my favourite one), the above function call is equivalent to mymethod(myclass,arg1,arg1). % Note that the name you choose for "this" is arbitrary! So for a function call myclass.mymethod(arg1,arg1), the declaration must be function mymethod(this, arg1, arg2) instead, the convention is that the class instance will be prepended to the function's argument list. in OOP you'd have A(1)=-1 now as everythings an object reference.įurthermore, "native" matlab routines dont have a "this/self/me" variable that contains the instance reference to access from within functions. if you now set B(1) = -1 you'd hope that A(1) is still 1, right? this is because matlab keeps track of "copies" and truly creates them as you modify different variables initially set to the same matrix. Imagine you have a matrix A =, then assign that via B = A. The reason they have both in Matlab is that in Matlab you would expect the "value" behaviour natively. "value" classes are always returning a full clone of whatever object (which has been modified by what you just did, e.g. proper object instances with pointers to them. "handle" classes are what your mind is set to. % p2 is also an instance of Polynomial with p's state at assignmentĪnd of a Handle class is % db is an instance of Database To paraphrase their illustration, the behavior of a Value class is % p is an instance of Polynomial The Mathworks has a good rundown on this topic. Assigning a Handle class instance to a variable create a reference (alias) to that instance.Assigning a Value class instance to a variable creates a copy of that class.Going a bit deeper, the difference between a Value class and a Handle class lies mostly in assignment: Handle classes ( classdef Person < handle) do not need to return the modified object (like returning void): function = set.name(obj,name) that modify the object must return a modified object to copy over the existing object variable". Since your class is currently a subclass of the default Value class, your setters need to return the modified object: function obj = set.name(obj,name)įrom the documention: "If you pass to a function, the function must return the modified object." And in particular: "In value classes, methods.
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