Composition Prasun Dewan Department of Computer Science University

Composition Prasun Dewan Department of Computer Science University of North Carolina CB 3175 Sitterson Hall Chapel Hill, NC 27599 -3175 dewan@cs. unc. edu http: /www. cs. unc. edu/~dewan 6/13/2021 290 -63: Composition 1

Example 6/13/2021 290 -63: Composition 2

Class Decomposition Model Controller Bar. View 6/13/2021 Semantics State 5 Manipulates State Displays state 290 -63: Composition 3

Reuse Model Controller Text. View 6/13/2021 Semantics State Manipulates State Displays state 290 -63: Composition 4

Inheritance-based Composition IS-A Model Controller Bar. View 6/13/2021 290 -63: Composition 5

Inheritance-based Composition Model Controller Text. View 6/13/2021 290 -63: Composition 6

Inheritance-based Composition Model Text. View Controller 6/13/2021 290 -63: Composition 7

Inheritance-based Composition Model Text. View MController 6/13/2021 290 -63: Composition Menus 8

Delegation & MVC Has-A Model increment Controller Push Button 6/13/2021 Observerable/ Listenable model. Updated get. Val Editing View State Bar. View Editable Text. Field 290 -63: Composition Observer/ Listener Draw Bar 9

Reuse Model & Controller Has-A Model increment add. Listener Observerable/ Listenable model. Updated get. Val Controller Text. View Push Button 6/13/2021 Observer/ Listener Draw Text 290 -63: Composition 10

Multilevel MVC Model Controller Text. View Screen. View 6/13/2021 290 -63: Composition Screen Format 11

Multilevel MVC Model Controller Text. View Print. View 6/13/2021 290 -63: Composition Printer Format 12

Observer but Not View Model Replica Lateral Observer Spread. Cell Dependent Cell “Callback” Mouse 6/13/2021 Controller 290 -63: Composition Higher. Level Observer 13

Delegate but Not Observer Delegator Delegate Stack push add. Element Vector display. Int. Stack push 6/13/2021 display. Stack 290 -63: Composition 14

Delegate but Not Observer • Observer received “notification” about state change in Observable • Notification is Observable-Specific not Observer-specific. • Observer does not “depend” on Observable to do its tasks. 6/13/2021 290 -63: Composition 15

Delegation Vs Inheritance 6/13/2021 290 -63: Composition 16

Inheritance-based Composition IS-A Model Controller Bar. View 6/13/2021 290 -63: Composition 17

Delegation-Based Composition Model Controller 6/13/2021 Bar. View 290 -63: Composition 18

Reuse Model & View Model MController 6/13/2021 Text. View 290 -63: Composition 19

Delegation Vs Inheritance • Arbitrary class can be replaced 6/13/2021 290 -63: Composition 20

Dynamic View Switching 6/13/2021 290 -63: Composition 21

Dynamic View Switching 6/13/2021 290 -63: Composition 22

Dynamic Configuration in Delegation Model add. Listener(Text. View) remove. Listener(Bar. View) set. Model(Model) Controller 6/13/2021 Text. View Bar. View 290 -63: Composition 23

Compile-time binding in Inheritance Model Controller Bar. View 6/13/2021 290 -63: Composition 24

Delegation Vs Inheritance • Arbitrary class can be replaced • Dynamic component replacement • IS-A compile time • HAS-A runtime 6/13/2021 290 -63: Composition 25

Multiple Views 6/13/2021 290 -63: Composition 26

Multiple Instantiation in Delegation Model Bar. View 6/13/2021 Controller 290 -63: Composition Bar. View 27

Multiple Subclasses in Inheritance M_Vars Model M_Vars’ C_Vars Controller C_Vars’ BV_Vars 6/13/2021 Bar. View Text. View 290 -63: Composition TV_Vars 28

Multiple Instantiation in Delegation Model Bar. View TV_Vars 6/13/2021 M_Vars Controller Bar. View C_Vars B_Vars 290 -63: Composition 29

Delegation Vs Inheritance • Arbitrary class can be replaced • Dynamic component replacement • IS-A compile time • HAS-A runtime • Multiple Component Instantiation 6/13/2021 290 -63: Composition 30

Distribution in Delegation Model Controller 6/13/2021 Bar. View 290 -63: Composition 31

Distribution in Delegation Model Controller 6/13/2021 Bar. View Controller 290 -63: Composition Bar. View 32

Distribution in Inheritance Model Controller Bar. View 6/13/2021 290 -63: Composition 33

Proxies in Delegation Model Controller 6/13/2021 Out In Bar. View Controller 290 -63: Composition Model Bar. View 34

Delegation Vs Inheritance • Arbitrary class can be replaced • Dynamic component replacement • IS-A compile time • HAS-A runtime • Multiple Component Instantiation • Distribution • Proxies 6/13/2021 290 -63: Composition 35

Delegation Vs Inheritance n n n Connections made by component users O(N 2) connections explicitly made Connections not visualized 6/13/2021 n n n Connections specified by component definers O(n) connections explicitly made (components define an environment) Links Visualized 290 -63: Composition 36

Delegation Vs Inheritance n n n Connections remade with dynamic links Distribution requires more work and objects Ditto with Proxies 6/13/2021 n No dynamism n No distribution n No proxies 290 -63: Composition 37

Delegation vs Inheritance n n n 6/13/2021 Flexibility of Delegation => Less Automation Provide incremental path Some disadvantages not inherent and can be partially overcome 290 -63: Composition 38

Overcoming Delegation Drawbacks n Connections made by component users n n 6/13/2021 Connections specified by component definers External agent makes connection at instantiation time based on specification 290 -63: Composition 39

External Generic Agent Generic Composer Model Controller 6/13/2021 Text. View Bar. View 290 -63: Composition Specific Composer 40

Facets add. Listener() Model Generic Composer set. Model() Controller 6/13/2021 Text. View Bar. View 290 -63: Composition Specific Composer 41

Registering add. Listener() Model Generic Composer reg(c, m, v) set. Model() Controller 6/13/2021 Text. View Bar. View 290 -63: Composition reg(C, M, V) Specific Composer 42

Auto Connection add. Listener() Model Generic Composer reg(c, m, v) set. Model() Controller Text. View Bar. View AC(c, m, v) Specific Composer 2*n runtime 6/13/2021 290 -63: Composition 43

Auto Connection add. Listener() Auto-connect Facets Model reg(C, M, V) set. Model() Controller 6/13/2021 Generic MVC Composer Text. View 290 -63: Composition AC(new C) Specific Composer n + 1 runtime 44

Dynamic/Explicit Connection 6/13/2021 290 -63: Composition 45

Connection Visualization 6/13/2021 290 -63: Composition 46

Specifying Facets register. Facet (<Facet. Name>, <Facet. Type>, <Method>, arity) register. Facet (listener, Listener, add. Listener, many) add. Listener() Model Server-API Approach set. Model() Controller Text. View Bar. View Facet. Specification API Generic Composer Registration API Specific Composer register. Facet (changeable, Changeable, set. Model, single) 6/13/2021 290 -63: Composition 47

Specifying Facets register. Facet (listener, Listener, add. Listener, many) Facet. Reflection Specification Protocol API add. Listener() Model Introspection Approach set. Model() Controller Text. View Bar. View Generic Composer Registration API Specific Composer register. Facet (changeable, Changeable, set. Model, single) 6/13/2021 290 -63: Composition 48

Basic Connection Patterns public void set<Facet. Name> (<Facet. Type>) [public <Facet. Type> get<Facet. Name> ()] public void add<Facet. Name> (<Facet. Type>) [public Enumeration enumerate<Facet. Name> ()] public void remove<Facet. Name> (<Facet. Type>) public <Facet. Type> <Facet. Name> 6/13/2021 290 -63: Composition 49

Some Advanced Patterns public class Controller implements Auto. Connect. All public String[] get. Auto. Connect. Facets() [public String get. Opposite<Facet. Name>()] [public Object get. Reference. For<Facet. Name>()] Argument to set<Facet. Name> (<Facet. Type>) 6/13/2021 290 -63: Composition 50

Facet Description API public void set. Opposite. Facet (<Object>, <Source. Facet>, <Dest. Facet> 6/13/2021 290 -63: Composition 51

General Connection a: ta u tu tv v b: tb a: ta connect (a, u, b, v) 6/13/2021 290 -63: Composition 52

Direct Connection a: ta u tbu tav vv b: tb connect (a, u, b, v) Direct. Connect(A, U, B, V) -> facet (A, U); facet (B, V); type (A, Ta), type (B, Tb); type(U, Tu), type (V, Tv); subtype (Ta, Tv); subtype (Tb, Tu); colocated(A, B) or (subtype (Ta, Remote); subtype (Tb, Remote)); do. Connect (A, U, B, V) 6/13/2021 290 -63: Composition 53

Proxy-based Connection a: ta u tu tw w ap a: t p: t x tx tv v b: tb a: ta proxy (p, a, u, w, x, v, b) connect (a, u, b, v) Proxy. Connect (P, A, U, W, X, V, B) -> connect (A, U, P, W); connect (P, X, B, V) 6/13/2021 290 -63: Composition 54

Interposition X Client a: ta X Pseudo Server u tbu xb taw vw p: a: u x t b a a t tt, pt p: X Server tva v b: tb a: ta connect (a, u, b, v) 1. connect (A, U, B, V) -> proxy(P, A, U, V, B); interpose (P); Proxy. Connect (P, A, U, V, B) 2. connect(A, U, B, V) -> Direct. Connect (A, U, B, V) 6/13/2021 290 -63: Composition 55

Type Translation: Adapter Lock-Floor Translation Lock Controller a: ta u tu taw w v p: tp ux txb Floor Controller tv v b: tb a: ta connect (a, u, b, v) 3. connect (A, U, B, V) -> proxy(P, A, U, V, B); Proxy. Connect (P, A, U, V, B) 6/13/2021 290 -63: Composition 56

Right Facet Translation a: ta u tu taw w v ap a: t p: t x txb tv v b: tb a: ta connect (a, u, b, v) 4. connect (A, U, B, V) -> proxy(P, A, U, V, X, V, B); Proxy. Connect (P, A, U, W, X, V, B) 6/13/2021 290 -63: Composition 57

Left Facet Translation Observable a: ta Changeable Coupler u tu taw w ap a: t p: t u txb tv v b: tb a: ta connect (a, u, b, v) 5. connect (A, U, B, V) -> proxy(P, A, U, W, U, V, B); Proxy. Connect (P, A, U, W, X, V, B) 6/13/2021 290 -63: Composition 58

General Facet Translation Observable a: ta Changeable Coupler u: tu taw w ap a: t p: t x txb tv v b: tb a: ta connect (a, u, b, v) 6. connect (A, U, B, V) -> proxy(P, A, U, W, X, V, B); Proxy. Connect (P, A, U, W, X, V, B) 6/13/2021 290 -63: Composition 59

Delegation Vs Inheritance n n n Connections made by component users O(N 2) connections explicitly made Connections not visualized 6/13/2021 n n n Connections specified by component definers O(n) connections explicitly made (components define an environment) Links Visualized 290 -63: Composition 60

Manual Vs Assisted Delegation n Connections made by component users O(N 2) connections explicitly made Connections not visualized 6/13/2021 n n n Connections specified by component definers/ registrars 1 - O(N 2) connections explicitly made (components define an environment) Links Visualized 290 -63: Composition 61

Delegation vs Inheritance n n n 6/13/2021 Flexibility of Delegation => Less Automation Provide incremental path Some disadvantages not inherent and can be partially overcome 290 -63: Composition 62