MATLAB: Copy a handle of an Array

array handle reference copyMATLAB

I want a method to copy a handle of an Array not the Array Elements. like the java Arrays. for Example: X = [3 3 3]; A = handle(X); so when I change A, X will Automatically changed. so: A(2) = 0; will case that x = 3 0 3

Best Answer

You cannot do it. While MATLAB supports handle classes, you cannot subclass double to be a handle class. There are a number of different ways to work around the problem, can you provide more about what you want to do?

If you are simply trying to avoid memory issues, MATLAB handles that behind the scenes and often there isn't a memory advantage between passing arrays, handles or pointers.

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MATLAB: Using Mex with Classes

One option is to keep your pointer in a high level variable (i.e., global) and set up a mexAtExit function to clean things up when the function is cleared. E.g.,

void *handle = NULL; // not sure of type here ... you didn't declare it above
void clear_handle(void)
{
    if( handle ) {
        exit_hw(handle);
        handle = NULL;
    }
}
void mexFunction( ...parms... )
{
if( !handle ) {
    handle = init_hw();
    if( !handle ) {
        mexErrMsgTxt("Unable to init handle.");
    }
    mexAtExit(clear_handle);
}
alloc_mem(handle);
get_data();
copy_to_mxDoubleMatrix();
}

Only on the first call init_hw is called and the handle remembered. When you clear this routine from memory, exit_hw is called to clean things up.

MATLAB: Lisning for a subclass property

First, a matter of terminology. Your subclass is not a subclass at all. A subclass derives from the main class. In matlab OOP this implies the following definition:

classdef subclass < mainclass

Your subclass is just a standard class that happens to be a member of your main class. It would be very odd for a main class to instantiate a subclass (except through factory methods), anyway.

In any case, If you want to listen to the property changes of your member class, it is these properties you need to set observable and these properties you need to attach a listener. At present, the only thing you'll detect is if your subclass member is changed to a new instance. That is you'll detect this:

m.subclass = class_subclass; %assign a new class_subclass to the member property of m

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MATLAB: Using Mex with Classes

MATLAB: Lisning for a subclass property

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