17.4: Object-Oriented Programming, Part 2
- Page ID
- 103745
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Author: Randy Matusky
This is from section "Object-Oriented Programming (OOP)" of this link:
https://oercommons.org/authoring/4896-matlab-an-introductory-course/view
Introduction to OOP
Object-oriented programming (OOP) applies to the development of software or “objects” that have data fields (attributes that describe the object) and associated procedures known as methods. Objects are composed of two elements: data, such as numbers, strings or variables and actions such as functions. You can then combine objects or have them interact together in order to design applications and computer programs. Examples of object-oriented programming languages include Objective-C, Smalltalk, Java and C#.
Classes
One of the first distinctions you must make before trying to create programs in MATLAB is the difference between classes and objects. A class is a definition that specifies certain characteristics that all instances of the class share. These characteristics are determined by the properties, methods and events that define the class and the values of attributes that modify the behaviour of each of these class components. Class definitions describe how objects of the class are created and destroyed, what data the objects contain, and how you can manipulate this data.
Objects contain actual data for a particular entity that is represented by the class. An example to help better explain the difference is to think that a class is like a bank account, while an object is one specific bank account that includes a real account number.
The following table will help you better understand other common definitions used in MATLAB.
| Term | Definition |
| Class Definition | Description of what is common to every instance of a class. |
| Properties | Data storage for class instances. |
| Methods | Special functions that implement operations that are usually performed only on instances of the class. |
| Events | Messages that are defined by classes and broadcasts by class instances when some specific action occurs. |
| Attributes | Values that modify the behaviour of properties, methods, events, and classes. |
| Listeners | Objects that respond to a specific event by executing a callback function when the event notice is broadcast. |
| Objects | Instances of classes, which contain actual data values stored in the objects' properties. |
| Subclasses | Classes that are derived from other classes and that inherit the methods, properties, and events from those classes (subclasses facilitate the reuse of code defined in the superclass from which they are derived). |
| Superclasses | Classes that are used as a basis for the creation of more specifically defined classes (i.e., subclasses). |
| Packages | Folders that define a scope for class and function naming. |
Defining A Class
The first step to defining a class is by creating a new m-file with the same name as the class you want to create. You need to start the file with the classed keyword followed by the class name. The following line is for defining the properties and methods of the class. A special keyword called the constructor is needed to create or construct a new object, and it must have the same name as the class. the constructor can take any argument which specifies initial values for the properties, and must return one argument, the constructed object. Properties can optionally be assigned default values. If no default is specified and no value is assigned by the constructor, they are assigned the empty matrix.
The following is an example of how to create a class in MATLAB:
how to create a class in MATLAB
| Line | Explanation |
| classdef mydate | This is where you write a description of the class |
| function obj = mydate (minute, hour, day, month, year) | This is the class constructor |
Solution
Add example text here.
.
Create Class Objects
Now that you have created the class, you can create date objects. The following two lines are examples of how you can create date objects.
d1 = mydate (0, 5, 20, 5, 1990);
d2 = mydate ();
The properties that you have just defined are public, meaning that they are accessible from outside the class. You can access and assign them using dot notion:
day = d1.day;
d1.year = 1990;
.