11.1: Object-Oriented Programming Basics
- Page ID
- 117592
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)By the end of this section you should be able to
- Describe the paradigm of object-oriented programming (OOP).
- Describe the concepts of encapsulation and abstraction as they relate to OOP, and identify the value of each concept.
Grouping into objects
Object-oriented programming (OOP) is a style of programming that groups related fields, or data members, and procedures into objects. Real-world entities are modeled as individual objects that interact with each other. Ex: A social media account can follow other accounts, and accounts can send messages to each other. An account can be modeled as an object in a program.
Consider the example above. Which is a field in Ellis's 12/18/23 post?
- Ellis's followers list
- Ellis's username
- Answer
-
b. Ellis's username represents the post creator.
What does an object typically model in object-oriented programming?
- program code
- real-world entity
- Answer
-
b. An object models a real-world entity with fields and procedures.
Encapsulation
Encapsulation is a key concept in OOP that involves wrapping data and procedures that operate on that data into a single unit. Access to the unit's data is restricted to prevent other units from directly modifying the data. Ex: A ticket website manages all transactions for a concert, keeping track of tickets sold and tickets still available to avoid accidental overbooking.
Consider the example above. Suppose the venue has to be changed due to inclement weather. How should a programmer change the website object to allow changes to the Venue field?
- Add a procedure to change the field.
- Allow users direct access to the field.
- No valid way to allow changes to the field.
- Answer
-
a. A procedure, such as
Change venue, can make changes to the field and protect the field from inappropriate access.
Which is a benefit of encapsulation when developing complex programs?
- All objects can easily access and modify each other's data.
- Each object's data is restricted for intentional access.
- Answer
-
b. Limiting data access prevents accidental changes and makes relationships between objects clearer.
Abstraction
Abstraction is a key concept in OOP in which a unit's inner workings are hidden from users and other units that don't need to know the inner workings. Ex: A driver doesn't usually need to know their car engine's exact, numerical temperature. So the car has a gauge to display whether the engine temperature is within an appropriate range.
Consider the car example in the paragraph above. Suppose the designer decided to remove the engine temperature indicator. Would this be a good use of abstraction?
- yes
- no
- Answer
-
b. Correct abstraction makes only necessary information visible. An overheated engine can cause irreparable damage, so an indicator is necessary for the driver.
Which is a benefit of abstraction?
- improved view of information
- high visibility of information
- Answer
-
a. Showing only the necessary information reduces clutter and improves the overall experience.