OOP, API Design and MVP
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OOP, API Design and MVP



Presentation on the principles, philosophy and a few applications of object oriented programming along with a few pointers on how to effectively code. Presented at a session aimed at undergrad ...

Presentation on the principles, philosophy and a few applications of object oriented programming along with a few pointers on how to effectively code. Presented at a session aimed at undergrad computer science students at the University of Pune.
Present along with Mr. Anirudh Tomer and Mr. Toshish Jawale.



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OOP, API Design and MVP OOP, API Design and MVP Presentation Transcript

  • SOLID OOPSConvertingReal world entities into programming Objects ; understanding its applications ; API designing, MVC framework
  •  We apologize for wrong session title  Lets know each other Your expectations Our aim Why should you join this session Goodies for active participants Introduction
  •  What is “Real”? Everything outside of your program is Real. Even your own program is a Real World Entity for some other program or even for your own program! In shortReal World Entity… View slide
  •  Because these are all the “things” on which we want to work upon. Yes, and by work we do not mean, just writing the code! Why do we bother about this? View slide
  •  Objects? Why? How are they introduced in the programming world? Where are they used often? State and behaviour Who should use it?Correlating to programmingobjects
  •  We separate our real world entities in different groups Object is an instance of a class Ball instances ofWhat is this class?
  •  How classes are organized? Why classes need to be organized? Is there any standard way to do it? If yes, whats it?Organization
  •  How these different attributes of a class are defined? fields/properties - state methods/functions - behavior constructors/initializers destructorsWhat class contains?
  •  What is the object oriented way of getting rich ? — Inheritance Relations between the classes By the way, are you good at relations?Relations
  •  Have you watched Television?Interface
  •  Something you use to keep your stuff from mixing together Folders Drives A customized, more sophisticated package Examples familiar to you are, ◦ ZIP file ◦ EXE file ◦ DLL file etc.Point is, keep your stuff organized.Package
  • What is Abstraction?• Abstraction - a concept or idea not associated with any specific instance• It is all about perspective
  • Where does abstraction exist?• Control abstraction o Abstraction of actions• Data abstraction o Abstraction of information
  • How does this relate toprogramming?• Writing functions/subroutines is control abstraction.• Datatypes is data abstraction.
  • Data Abstraction• Generalization• Specialization
  • Examplepublic class Animal extends LivingThing{ theChicken = new Animal(); private Location loc; theCat = new Animal();if private double energyReserves; (theChicken.isHungry()) public boolean isHungry() { { return energyReserves < 2.5; theChicken.eat(grains);} } if (theCat.isHungry()) { public void eat(Food f) { theCat.eat(mouse);} // Consume food theCat.moveTo(theSofa); energyReserves += f.getCalories(); } public void moveTo(Location l) { // Move to new location loc = l; }}
  • Its relevance with OOP• Object is an attempt to combine data and control abstraction• Polymorphism• Inheritence
  • Why do this?• Separate the business logic from the underlying complexity• Make it easier to parallelize tasks• Meaningful amount of details are exposed• Representation in a similar form in semantics (meaning) while hiding implementation details.
  • Why do we write programs?
  • We have the right objects inplace, now what?• Lets get them talking to each other• Lets actually tell them what to talk about
  • What sort of messages?• Creation• Invocation• Destruction
  • Who generates thesemessages?• Aliens? • Platform• The Government? • User Interaction • Events
  • API Designing
  • String operations I need it to be Hehehe! The menu driven whole 2 hours I will just write a fancy menu Programming Lab I
  • Set operations Again! *$%#@ I need it to be Menu will be menu driven “Enter 1 to proceed 0 to exit” Programming Lab I
  • Don’ts we do Monolithic programs Single file containing all functions Code repetition Thinking less about function signature Reinventing the wheel
  • What we think about API  API
  • What it actually is  printf(), scanf(), strcmp() Easy to use and hard to misuse Spec of DS, functions, Can be programming language unspecific!! behavior etc. Not necessarily a code library, can be just a spec You can create your own API too
  • Lets design an API
  • Designing Process (based on suggestions by Joshua Bloch) Write 2 programs and not one Write API first ◦ Understand the use case ◦ Foresee future extensions (don’t change API often) ◦ A general purpose API vs multiple small API’s ◦ If you can’t name it, its doing either extra or doing less ◦ Don’t surprise the API user, don’t do extra ◦ Remember! You can always add but you can’t remove ◦ Document the API religiously! ◦ Use consistent parameter ordering. ◦ Extra params, use a struct Code more! API is living thing Expect to make mistakes. Refactor API! Encourage others to use it
  • MVC Architecture
  • Programming without MVC I need it Linked List with GUI o add a node o remove a node o reverse a linked list Linked list with GUI ______ ______ ______|__1__| |__5__| |__7__| …
  • Challenges Data Functions GUI Structures • Function • Creating • struct ? signature boxes • Separate • Flow control • Moving variables boxes
  • Nightmare beginstypedef struct node{ struct node* nextNode;…}Node;…Node *linkedlist;addNewNode(){ while (linkedlist->nextNode!=null){ drawSquare(); //you may have internal D.S. for each square drawArrow(); } Node *newNode = (Node*) malloc(sizeof(struct node)); scanf(); // for new values newNode->val1 = …; newNode->val2 = …; linkedlist->nextNode = newNode; while (linkedlist->nextNode!=null){ drawSquare(); drawArrow(); }}
  • New requirements Keep different colors for each node I want oval nodes not rectangular nodes I want linked list nodes to be shown in hierarchy not in straight line. Make Changes
  • FB Timeline: Full of GUIComponents
  • MVC Framework: Coding vs.Architecting Its nothing but how you design your code.
  • Model View Controller• Handling data • Display data • Read data• Save them on from view file or in • Control user internal D.S interaction • Send new data to modelRoles: Model, View and Controller
  • M-V-C not MVC Keep them separate You may create different files ◦ A separate “model.h” ◦ A separate “view.c” (includes model.h) ◦ A separate “controller.c” (includes model.h) ◦ Give deep thought to data structures Principle of Agnosticism: each component is unaware of others presence
  • Modeltypedef struct node{ C++ or other struct node* nextNode; int id; OOP languages … make finding the}Node;int globalId = 0; context easytypedef struct linkedList{ Node * headNode; int id; int listLength;}LinkedList;LinkedList *linkedListPool[];void addNode(int linkedListId, int index, Node *newNode){ …}void removeNode(int linkedListId, Node *node){ …}LinkedList* createNewLinkedList(){ LinkedList* newll = (LinkedList*) malloc(sizeof(struct linkedList)); newll->id = globalId++; newll->headNode = (Node*) malloc(sizeof(struct node)); newll->length = 0; linkedListPool[globalId] = newll; return newll;}
  • Viewtypedef struct viewNode{ struct viewNode* nextViewNode; int xLocation, int yLocation; String color; //#FF3e2A (in hex)…}ViewNode;//Similar to Model create another structtypedef struct display{ ViewNode* head; int id; int length;}Display;Display *displayNodeList[];void addDisplayNode(int viewNodeId, int index, Node *newNode){ //create new ViewNode //Render UI …}//create new display node like Model
  • Controllertypedef enum input{ ADD,REMOVE,GET_LENGTH…}Input;LinkedList* linkedList = createNewLinkedList();Display* display = createNewDisplay();//Show a fancy menuInput input = read input from user;switch(input){ case ADD: Node* newNode = //malloc new node; addNode(linkedList->id,newNode); addDisplayNode(display->id,newNode); break;}
  • Questions ?