Software Design Patterns Exam 4

Front 1

Template Method

purpose & example

Back 1

• Purpose: abstract out common behaviors
  
  
• Web UI dashboard w/ content panels
• Panel => shares the getUser(), and build() operations
• GradesPanel => overloads the getTitle(), getBody(), getColor() operations
  

Front 2

Composite pattern

purpose & example

Back 2

• purpose: perform opts on both primitive & composite in same way
  
  
• file system
  
• file => primitive
• directory => composite
• abstractFile => component/interface

Front 3

Proxy pattern

purpose & example

Back 3

• purpose: provide a placeholder or surrogate for some other object in order to control access when costly (time, memory, etc)
  
  
• Document editor (loading images costly)
• TextDocument, getProxyImage() (in memory)
• ImageProxy, name, getRealImg() (memory)
• Image : imageData (on disk)
  

Front 4

Iterator pattern

purpose & example

Back 4

• purpose: traverse a collection and access its elements without exposing structure
  
  
• PHP: foreach( obj in collec ) {}
• JS: ._each( rows, function(row){} )
• CF: for( row in rows ) {}

Front 5

Mediator pattern

purpose & example

Back 5

• purpose: encapsulate how objects interact with each other (complex interactions)
  
  
• air traffic control tower

Front 6

What is TIMPC?

Back 6

Template, Iterator, Mediator, Proxy, Composite

Front 7

What design principals with Template?

Back 7

• Open/Close
  
• Inversion of Control (abstract calls subclass method)
  

Front 8

What patterns are used with Template?

Back 8

• Inheritance
• Composition with strategy (example game class calls print)

Front 9

What are some types of proxies?

Back 9

• remote: local placeholder for remote thing
  
• virtual: creates objects on demand
  
• protection: access control to an object smart
  
• smart reference: performs additional things when object is accessed (pass-thru functions)

Front 10

What type of proxy is a variant on the Adapter pattern?

Back 10

SMART REFERENCE

interposes extra function between proxy and realSubject

Front 11

What are the common operations in an ITERATOR interface?

Back 11

• Current() - points to a specifc element
  
• Next() - moves itself to next element
  
• Reset() - sets to starting element
  
• IsEnd() - detects if end of collection
  

Front 12

Why use a mediator pattern?

Back 12

• Limits subclassing - localizes behavior
• Decouples colleagues, encourages reuse
• Simplified interactions, m2many to m2one
• Abstracts cooperation
• Centralized controll