Object Oriented Design

SOLID principles

dmitry.kandalov@db.com

Why?

Why I still program?

NO hacking

NO nerds

NO bit-twiddling

Literate programming

Why design?

maintenance

less bugs

reuse?

peace of mind

satisfaction

fun

principles != rules

Single Responsibility

Principle

Portfolio

Book

InstrumentPosition

value: double

Main

ServiceClient

2: new 3: use

1: new

4: use

Main

ServiceClient

Context

2: use

3: use

1.2: new 1.1: new

1: new

Open/Closed Principle

TG

<<interface>>

BPCListener

<<interface>>

BPCManager

<<interface>>

SnapshotProvider

uses

supply

notify

requests

create

OCP is emergent

Liskov Substitution Principle

@IViolateLSP

Interface Segregation Principle

BookPositionNode

<<interface>>

ResubscribingNode AbsPosNode

StateMachine

NodeUser

uses

uses

<<interface>>

BigService

<<interface>>

Service1<<interface>>

Service2<<interface>>

Service3

Client1 Client2 Client3

Dependency Inversion Principle

Client Service

Client<<interface>>

Service

ServiceImpl

Client

<<interface>>

ServiceServiceImpl

client

service

Client<<interface>>

Service

ServiceImpl

client

service

Client<<interface>>

Service

ServiceImpl

client

service

api

SRP

OCP

LSP

ISP

DIP

REP

CRP

CCP

ADP

SDP

SAP

What else?

idea code

F**k Design

Zen Coding

not scalable

totally art

Thanks!