Object-Oriented Programming Onramp, Overloading Operators

Hallo Harald,

meine Frage bezieht sich auf die Erläuterungen auf dieser Seite:

Overloading and Precedence

Mit x und y werden zwei Instanzen der Klasse foo erzeugt. Anschließend werden beide multipliziert. Wo wird die Information in der Tabelle (Zuordnung der Operatoren zu den Funktionen) hinterlegt?

Vielen Dank!

Lisa

Answer 1

[Vandit]

Hello Elisabeth,

The information about how operators are associated with functions in MATLAB is part of MATLAB's object-oriented programming design. When you define a class, you can overload built-in MATLAB functions and operators for instances of that class by implementing methods with specific names. The table provided shows some of these associations:

• a + b is associated with the plus(a, b) method.
• a - b is associated with the minus(a, b) method.
• a .* b is associated with the times(a, b) method.
• a * b is associated with the mtimes(a, b) method.
• a < b is associated with the lt(a, b) method.
• a == b is associated with the eq(a, b) method.

In the context of the 'foo' class you provided, when you perform the operation z = x * y, MATLAB internally calls the "mtimes" method defined in your class (since * is associated with "mtimes"). This is because the "mtimes" method is specifically designed to handle the * operator for objects of your class. The "mtimes" method you've implemented in turn calls the "times" method (via the .* operator within the "mtimes" method), which performs element-wise multiplication of the 'Values' properties of the two 'foo' objects and returns a new 'foo' object with the result.

For a comprehensive listing of all MATLAB operators, symbols, and special characters, along with their corresponding functional equivalents, please refer to the following documentation:

https://www.mathworks.com/help/matlab/matlab_prog/matlab-operators-and-special-characters.html

Hope this helps.

[Elisabeth]

Hello Vandit,

thank you for you answer! I understand that somewhere in a code the behaviour of operators must be defined (in that case by special functions to customize the behaviour of different operators like +,-,...). I don't know how to classify Matlab compared to C and C++. C++ supports operator overloading but Matlab is based on C, right? (What exactly is Matlab, since its based on C but not C++ but knows classes?) Can I look up the implementation of the table, you've mentioned above, somewhere?

Elisabeth