MATLAB Handle Class vs Value Class Differences

1. Copy Behavior

Value Class:
Assigning a value object to a new variable creates an independent copy. Modifying the copy does not affect the original.
matlab

Copy
```
obj1 = MyValueClass();
obj2 = obj1;   % Independent copy of obj1
obj2.Data = 5;  % obj1.Data remains unchanged
```

Handle Class:
Assigning a handle object copies the reference, not the data. Both variables point to the same object.

obj1 = MyHandleClass();
obj2 = obj1;   % Both reference the same object
obj2.Data = 5;  % obj1.Data is also updated to 5

2. Memory and Performance

Value Class:
May incur memory overhead when copying large objects repeatedly.
Handle Class:
Efficient for large data, as multiple references share the same instance without duplication.

3. Function Argument Handling

Value Class:
Passed by value. Modifications inside a function do not affect the original unless explicitly returned and reassigned.
matlab

Copy
```
function modifyValue(obj)
    obj.Data = 10;  % Modifies a local copy
end
```
Handle Class:
Passed by reference. Changes in a function directly affect the original object.
matlab

Copy
```
function modifyHandle(obj)
    obj.Data = 10;  % Original object is modified
end
```

4. Methods and Features

Handle Class:
- Inherits from handle, enabling methods like addlistener, notify, and delete (destructor).
- Supports events and listeners for reactive programming.
- Destructor (delete) is called automatically when the object is destroyed.
matlab

Copy
```
classdef Sensor < handle
    events
        DataUpdated
    end
    methods
        function delete(obj)
            disp('Sensor object deleted');
        end
    end
end
```
Value Class:
No built-in support for events or destructors. Copying is explicit.

5. Equality Checks

Value Class:
== compares data equality (if the eq method is defined).
matlab

Copy
```
a = MyValueClass();
b = a;
a == b  % True (same data)
```

Handle Class:
== checks reference identity (whether two variables point to the same object).

a = MyHandleClass();
b = a;
c = MyHandleClass();
a == b  % True (same reference)
a == c  % False (different references)

6. Use Cases

Value Class:
- Immutable data (e.g., mathematical vectors).
- When independent copies are needed (e.g., configuration settings).
Handle Class:
- Shared resources (e.g., GUI components, file I/O).
- Large datasets to avoid memory duplication.
- Observer patterns (using events/listeners).

Example Code Snippets

Value Class:

classdef Point2D
    properties
        X
        Y
    end
end

Handle Class:

classdef Logger < handle
    properties (Access = private)
        LogData
    end
    methods
        function log(obj, message)
            obj.LogData{end+1} = message;
        end
    end
end

Summary Table

Feature	Value Class	Handle Class
Copy Behavior	Independent copies	Shared reference
Memory Efficiency	Higher overhead with copies	Efficient for shared data
Function Arguments	Requires return/reassign	Directly modifies original
Events/Destructors	Not supported	Supported (`addlistener`, `delete`)
Equality Check	Compares data	Compares references

Use handle classes for shared state or large data, and value classes for independent, immutable instances.