Kas iš tikrųjų yra programavimo paradigma?

Bet kuris kvailys gali parašyti kodą, kurį supranta kompiuteris. Geri programuotojai parašo žmonėms suprantamą kodą.

- Martinas Fowleris

Programuojant visada sudėtingumas yra priešas. Iš pradžių atrodo labai sudėtingos programos, kuriose yra daug judančių dalių ir vienas nuo kito priklausančių komponentų. Tačiau norint suprasti realaus pasaulio problemą paprastu ar elegantišku sprendimu reikia giliau suprasti.

Kurdami programą ar spręsdami paprastą problemą, dažnai sakome: „Jei turėčiau daugiau laiko, būčiau parašęs paprastesnę programą“. Priežastis ta, kad mes sukūrėme sudėtingesnę programą. Kuo mažiau sudėtingumo, tuo lengviau derinti ir suprasti. Kuo programa tampa sudėtingesnė, tuo sunkiau ją dirbti.

Pagrindinis sudėtingumo valdymas yra programuotojo rūpestis . Taigi, kaip programuotojai susiduria su sudėtingumu? Yra daugybė bendrų metodų, kurie sumažina programos sudėtingumą arba leidžia ją lengviau valdyti. Vienas pagrindinių požiūrių yra programavimo paradigma. Pasinerkime į programavimo paradigmas!

Įvadas į programavimo paradigmas

Programavimo paradigmos terminas reiškia programavimo stilių . Joje kalbama ne apie konkrečią kalbą, bet apie tai, kaip jūs programuojate.

Yra daugybė gerai žinomų programavimo kalbų, tačiau joms visoms reikia įgyvendinti tam tikrą strategiją. Ir ta strategija yra paradigma.

Programavimo paradigmų tipai

Imperatyvi programavimo paradigma

Žodis „imperatyvas“ kilęs iš lotynų kalbos „impero“, reiškiančio „Aš liepiu“.

Tai tas pats žodis, iš kurio gauname „imperatorius“, ir tai gana taikliai. Tu esi imperatorius. Jūs duodate kompiuteriui nedaug nurodymų, kuriuos reikia atlikti, ir jis juos atlieka po vieną ir pateikia ataskaitas.

Paradigma susideda iš kelių teiginių, o juos visus įvykdžius, rezultatas yra saugomas. Tai yra parašyti instrukcijų sąrašą, nurodantį kompiuteriui, ką daryti žingsnis po žingsnio.

Privalomoje programavimo paradigmoje žingsnių tvarka yra labai svarbi, nes duotas žingsnis turės skirtingas pasekmes, priklausomai nuo dabartinių kintamųjų reikšmių, kai veiksmas bus vykdomas.

Norėdami tai iliustruoti, suraskime pirmųjų dešimties natūraliųjų skaičių sumą imperatyviosios paradigmos požiūriu.

C pavyzdys:

#include  int main() { int sum = 0; sum += 1; sum += 2; sum += 3; sum += 4; sum += 5; sum += 6; sum += 7; sum += 8; sum += 9; sum += 10; printf("The sum is: %d\n", sum); //prints-> The sum is 55 return 0; }

Ankstesniame pavyzdyje mes nurodome kompiuteriui, ką daryti eilutė po eilutės. Galiausiai saugome vertę ir ją atspausdiname.

1.1 Procedūrinio programavimo paradigma

Procedūrinis programavimas (kuris taip pat yra būtinas) leidžia šias instrukcijas suskaidyti į procedūras .

PASTABA: Procedūros nėra funkcijos. Skirtumas tarp jų yra tas, kad funkcijos grąžina vertę, o procedūros - ne. Tiksliau sakant, funkcijos yra sukurtos taip, kad turėtų minimalų šalutinį poveikį, ir visada sukuria tą patį išėjimą, kai gaunama ta pati įvestis. Kita vertus, procedūros neturi jokios grąžos vertės. Jų pagrindinis tikslas yra atlikti nurodytą užduotį ir sukelti norimą šalutinį poveikį.

Puikus procedūrų pavyzdys būtų gerai žinomas ciklas. Pagrindinis „for loop“ tikslas yra sukelti šalutinį poveikį ir jis negrąžina vertės.

Norėdami tai iliustruoti, suraskime procedūrinės paradigmos požiūriu pirmųjų dešimties natūraliųjų skaičių sumą.

C pavyzdys:

#include  int main() { int sum = 0; int i =0; for(i=1;i The sum is 55 return 0; }

Aukščiau pateiktame pavyzdyje mes naudojome paprastą ciklą, kad surastume pirmųjų dešimties natūraliųjų skaičių sumą.

Kalbos, palaikančios procedūrinio programavimo paradigmą, yra šios:

  • C
  • C ++
  • „Java“
  • „ColdFusion“
  • Paskalis

Procedūrinis programavimas dažnai yra geriausias pasirinkimas, kai:

  • Yra sudėtinga operacija, apimanti priklausomybes tarp operacijų ir tada, kai reikia aiškiai matyti skirtingas programos būsenas („SQL loading“, „SQL loading“, „Network online“, „No audio hardware“ ir kt.). Paprastai tai tinka paleisti ir išjungti programas (Holligan, 2016).
  • Programa yra labai unikali ir dalijamasi keliais elementais (Holligan, 2016).
  • Programa yra statiška ir nesitikima, kad ji laikui bėgant labai pasikeis (Holligan, 2016).
  • Tikimasi, kad laikui bėgant prie projekto nebus pridėta nė vienos arba tik kelios funkcijos (Holligan, 2016).

Kodėl turėtumėte apsvarstyti procedūrinės programavimo paradigmos išmokimą?

  • Tai paprasta.
  • Lengvesnis būdas stebėti programos eigą.
  • Jis gali būti stipriai modulinis arba struktūrizuotas.
  • Reikia mažiau atminties: ji efektyvi ir efektyvi.

1.2 Objektinio programavimo paradigma

OOP yra populiariausia programavimo paradigma dėl savo unikalių pranašumų, tokių kaip kodo moduliškumas ir galimybė kodo atžvilgiu tiesiogiai susieti realaus pasaulio verslo problemas.

Į objektą orientuotas programavimas siūlo tvarų būdą rašyti spagečių kodus. Tai leidžia jums kaupti programas kaip pataisų seriją.

- Paulas Grahamas

Pagrindinės objektinio programavimo ypatybės yra klasė, abstrakcija, inkapsuliacija, paveldėjimas ir polimorfizmas.

Klasė yra šablonas arba Blueprint, iš kurių sukūrė objektus.

Objects are instances of classes. Objects have attributes/states and methods/behaviors. Attributes are data associated with the object while methods are actions/functions that the object can perform.

Abstraction separates the interface from implementation. Encapsulation is the process of hiding the internal implementation of an object.

Inheritance enables hierarchical relationships to be represented and refined. Polymorphism allows objects of different types to receive the same message and respond in different ways.

To illustrate, let's find the sum of first ten natural numbers in the object-oriented paradigm approach.

Example in Java:

public class Main { public static void main(String[] args) { Addition obj = new Addition(); obj.num = 10; int answer = obj.addValues(); System.out.println("The sum is = "+answer); //prints-> The sum is 55 } } class Addition { int sum =0; int num =0; int addValues(){ for(int i=1; i<=num;i++){ sum += i; } return sum; } }

We have a class Addition that has two states, sum and num which are initialized to zero. We also have a method addValues() which returns the sum of num numbers.

In the Main class, we've created an object, obj of Addition class. Then, we've initialized the num to 10 and we've called addValues() method to get the sum.

Languages that support the object-oriented paradigm:

  • Python
  • Ruby
  • Java
  • C++
  • Smalltalk

Object-oriented programming is best used when:

  • You have multiple programmers who don’t need to understand each component (Holligan, 2016).
  • There is a lot of code that could be shared and reused (Holligan, 2016).
  • The project is anticipated to change often and be added to over time (Holligan, 2016).

Why should you consider learning the object-oriented programming paradigm?

  • Reuse of code through Inheritance.
  • Flexibility through Polymorphism.
  • High security with the use of data hiding (Encapsulation) and Abstraction mechanisms.
  • Improved software development productivity: An object-oriented programmer can stitch new software objects to make completely new programs (The Saylor Foundation, n.d.).
  • Faster development: Reuse enables faster development (The Saylor Foundation, n.d.).
  • Lower cost of development: The reuse of software also lowers the cost of development. Typically, more effort is put into the object-oriented analysis and design (OOAD), which lowers the overall cost of development (The Saylor Foundation, n.d.).
  • Higher-quality software: Faster development of software and lower cost of development allows more time and resources to be used in the verification of the software. Object-oriented programming tends to result in higher-quality software (The Saylor Foundation, n.d.).

1.3 Parallel processing approach

Parallel processing is the processing of program instructions by dividing them among multiple processors.

A parallel processing system allows many processors to run a program in less time by dividing them up.

Languages that support the Parallel processing approach:

  • NESL (one of the oldest ones)
  • C
  • C++

Parallel processing approach is often the best use when:

  • You have a system that has more than one CPU or multi-core processors which are commonly found on computers today.
  • You need to solve some computational problems that take hours/days to solve even with the benefit of a more powerful microprocessor.
  • You work with real-world data that needs more dynamic simulation and modeling.

Why should you consider learning the parallel processing approach?

  • Speeds up performance.
  • Often used in Artificial Intelligence. Learn more here: Artificial Intelligence and Parallel Processing by Seyed H. Roosta.
  • It makes it easy to solve problems since this approach seems to be like a divide and conquer method.

Here are some useful resources to learn more about parallel processing:

  1. Parallel Programming in C by Paul Gribble
  2. Introduction to Parallel Programming with MPI and OpenMP by Charles Augustine
  3. INTRODUCTION TO PARALLEL PROGRAMMING WITH MPI AND OPENMP by Benedikt Steinbusch

2. Declarative programming paradigm

Declarative programming is a style of building programs that expresses the logic of a computation without talking about its control flow.

Declarative programming is a programming paradigm in which the programmer defines what needs to be accomplished by the program without defining how it needs to be implemented. In other words, the approach focuses on what needs to be achieved instead of instructing how to achieve it.

Imagine the president during the state of the union declaring their intentions for what they want to happen. On the other hand, imperative programming would be like a manager of a McDonald's franchise. They are very imperative and as a result, this makes everything important. They, therefore, tell everyone how to do everything down to the simplest of actions.

So the main differences are that imperative tells you how to do something and declarative tells you what to do.

2.1 Logic programming paradigm

The logic programming paradigm takes a declarative approach to problem-solving. It's based on formal logic.

The logic programming paradigm isn't made up of instructions - rather it's made up of facts and clauses. It uses everything it knows and tries to come up with the world where all of those facts and clauses are true.

For instance, Socrates is a man, all men are mortal, and therefore Socrates is mortal.

The following is a simple Prolog program which explains the above instance:

 man(Socrates). mortal(X) :- man(X). 

The first line can be read, "Socrates is a man.'' It is a base clause, which represents a simple fact.

The second line can be read, "X is mortal if X is a man;'' in other words, "All men are mortal.'' This is a clause, or rule, for determining when its input X is "mortal.'' (The symbol ":-'', sometimes called a turnstile, is pronounced "if''.) We can test the program by asking the question:

 ?- mortal(Socrates). 

that is, "Is Socrates mortal?'' (The "?-'' is the computer's prompt for a question). Prolog will respond "yes''. Another question we may ask is:

?- mortal(X).

That is, "Who (X) is mortal?'' Prolog will respond "X = Socrates''.

To give you an idea, John is Bill's and Lisa's father. Mary is Bill's and Lisa's mother. Now, if someone asks a question like "who is the father of Bill and Lisa?" or "who is the mother of Bill and Lisa?" we can teach the computer to answer these questions using logic programming.

Example in Prolog:

/*We're defining family tree facts*/ father(John, Bill). father(John, Lisa). mother(Mary, Bill). mother(Mary, Lisa). /*We'll ask questions to Prolog*/ ?- mother(X, Bill). X = Mary 

Example explained:

father(John, Bill).

The above code defines that John is Bill's father.

We're asking Prolog what value of X makes this statement true? X should be Mary to make the statement true. It'll respond X = Mary

?- mother(X, Bill). X = Mary 

Languages that support the logic programming paradigm:

  • Prolog
  • Absys
  • ALF (algebraic logic functional programming language)
  • Alice
  • Ciao

Logic programming paradigm is often the best use when:

  • If you're planning to work on projects like theorem proving, expert systems, term rewriting, type systems and automated planning.

Why should you consider learning the logic programming paradigm?

  • Easy to implement the code.
  • Debugging is easy.
  • Since it's structured using true/false statements, we can develop the programs quickly using logic programming.
  • As it's based on thinking, expression and implementation, it can be applied in non-computational programs too.
  • It supports special forms of knowledge such as meta-level or higher-order knowledge as it can be altered.

2.2 Functional programming paradigm

The functional programming paradigm has been in the limelight for a while now because of JavaScript, a functional programming language that has gained more popularity recently.

The functional programming paradigm has its roots in mathematics and it is language independent. The key principle of this paradigm is the execution of a series of mathematical functions.

You compose your program of short functions. All code is within a function. All variables are scoped to the function.

In the functional programming paradigm, the functions do not modify any values outside the scope of that function and the functions themselves are not affected by any values outside their scope.

To illustrate, let's identify whether the given number is prime or not in the functional programming paradigm.

Example in JavaScript:

function isPrime(number){ for(let i=2; i<=Math.floor(Math.sqrt(number)); i++){ if(number % i == 0 ){ return false; } } return true; } isPrime(15); //returns false

In the above example, we've used Math.floor() and Math.sqrt() mathematical functions to solve our problem efficiently. We can solve this problem without using built-in JavaScript mathematical functions, but to run the code efficiently it is recommended to use built-in JS functions.

number is scoped to the function isPrime() and it will not be affected by any values outside its scope. isPrime() function always produces the same output when given the same input.

NOTE: there are no for and while loops in functional programming. Instead, functional programming languages rely on recursion for iteration (Bhadwal, 2019).

Languages that support functional programming paradigm:

  • Haskell
  • OCaml
  • Scala
  • Clojure
  • Racket
  • JavaScript

Functional programming paradigm is often best used when:

  • Working with mathematical computations.
  • Working with applications aimed at concurrency or parallelism.

Why should you consider learning the functional programming paradigm?

  • Functions can be coded quickly and easily.
  • General-purpose functions can be reusable which leads to rapid software development.
  • Unit testing is easier.
  • Debugging is easier.
  • Overall application is less complex since functions are pretty straightforward.

2.3 Database processing approach

This programming methodology is based on data and its movement. Program statements are defined by data rather than hard-coding a series of steps.

A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database is usually controlled by a database management system (DBMS) ("What is a Database", Oracle, 2019).

To process the data and querying them, databases use tables. Data can then be easily accessed, managed, modified, updated, controlled and organized.

A good database processing approach is crucial to any company or organization. This is because the database stores all the pertinent details about the company such as employee records, transaction records and salary details.

Most databases use Structured Query Language (SQL) for writing and querying data.

Here’s an example in database processing approach (SQL):

CREATE DATABASE personalDetails; CREATE TABLE Persons ( PersonID int, LastName varchar(255), FirstName varchar(255), Address varchar(255), City varchar(255) );

The PersonID column is of type int and will hold an integer. The LastName, FirstName, Address, and City columns are of type varchar and will hold characters, and the maximum length for these fields is 255 characters.

The empty Persons table will now look like this:

Database processing approach is often best used when:

  • Working with databases to structure them.
  • Accessing, modifying, updating data on the database.
  • Communicating with servers.

Why are databases important and why should you consider learning database processing approach?

  • Massive amount of data is handled by the database: Unlike spreadsheet or other tools, databases are used to store large amount of data daily.
  • Accurate: With the help of built-in functionalities in a database, we can easily validate.
  • Easy to update data: Data Manipulation Languages (DML) such as SQL are used to update data in a database easily.
  • Data integrity: With the help of built-in validity checks, we can ensure the consistency of data.

Conclusion

Programming paradigms reduce the complexity of programs. Every programmer must follow a paradigm approach when implementing their code. Each one has its advantages and disadvantages.

If you're a beginner, I would like to suggest learning object-oriented programming and functional programming first. Understand their concepts and try to apply them in your projects.

For example, if you're learning object-oriented programming, the pillars of object-oriented programming are Encapsulation, Abstraction, Inheritance and Polymorphism. Learn them by doing it. It will help you to understand their concepts on a deeper level, and your code will be less complex and more efficient and effective.

I strongly encourage you to read more related articles on programming paradigms. I hope this article helped you.

Please feel free to let me know if you have any questions.

You can contact and connect with me on Twitter @ThanoshanMV.

Thank you for reading.

Happy Coding!

References

  • Akhilas Bhadwalas. (2019). Funkcinis programavimas: sąvokos, pranašumai, trūkumai ir programos
  • Alena Holligan. (2016). Kada naudoti OOP procesiniam kodavimui
  • Saylor fondas. (nd). Į objektą orientuoto programavimo (OOP) pranašumai ir trūkumai
  • Kas yra duomenų bazė | „Oracle“. (2019).