SlideShare a Scribd company logo

Visitor Pattern By Steve Hayes

•
•
M
melbournepatterns
TechnologyBusiness
1 of 53
Download to read offline
Visitor Steve Hayes Cogent Consulting Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
The Problem Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Show me everything in a consistent manner... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Show me everything in a consistent manner... ... and send it to my friend via email Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Show me everything in a consistent manner... ... and send it to my friend via email oh, and send it to her phone as well... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Show me everything in a consistent manner... ... and send it to my friend via email oh, and send it to her phone as well... and print it..... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Some analysis music please... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Commonality is in the eye of the beholder Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
With a little casual application of polymorphism... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Does this look bad to you? Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
The solution Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Visitors Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
“Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates” -- GOF Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
A solution to a problem in a context Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Headings, Details, ... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
and the Iterator Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Let’s show it in code! Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Time for visitors... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Melbourne Pushes Boundaries The Wolves in the Wall Redhill Consulting Pty Ltd - Ruby on Rails Plugins Let's talk about tests, baby... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Melbourne Pushes Boundaries Tim Colebatch Melbourne is experiencing its biggest growth surge since the 1960's The Wolves in the Wall 12.06 Redhill Consulting Pty Ltd - Ruby on Rails Plugins Here are some Ruby on Rails plugins we've developed... Let's talk about tests, baby... Some long babbling about test naming heuristics Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Cool! Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
When? Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
“an object structure contains many classes of objects with differing interfaces, and you want to perform operations on these objects that depend on their concrete classes” Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
“many distinct and unrelated operations need to be performed on objects in an object structure, and you want to avoid ‘polluting’ their classes with these operations.Visitor lets you keep unrelated operations together by defining them in one class. When the object structure is shared by many applications, use Visitor to put operations in just those applications that need them” Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Show me everything in a consistent manner... ... and send it to my friend via email oh, and send it to her phone as well... and print it..... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
“the classes defining the object structure rarely change, but you often want to define new operations over the structure. Changing the object structure classes requires redefining the interface to all visitors, which is potentially costly. If the object structure classes change often, then it’s probably better to define the operations in those classes” Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Consequences Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Visitor makes adding new operations easy Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
A visitor gathers related operations and separates unrelated ones Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Adding new ConcreteElement classes is hard Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Visitors can cross object hierarchies Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Visitors can accumulate state Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Visitors may compromise encapsulation Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
Discussion Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.

Recommended

The visitor design pattern
The visitor design patternThe visitor design pattern
The visitor design patternSamnang Chhun
 
An Introduction to
An Introduction to An Introduction to
An Introduction to melbournepatterns
 
State Pattern from GoF
State Pattern from GoFState Pattern from GoF
State Pattern from GoFmelbournepatterns
 
Iterator Pattern
Iterator PatternIterator Pattern
Iterator Patternmelbournepatterns
 
Iterator
IteratorIterator
Iteratormelbournepatterns
 
Concurrency Patterns
Concurrency PatternsConcurrency Patterns
Concurrency Patternsmelbournepatterns
 
Continuous Integration, Fast Builds and Flot
Continuous Integration, Fast Builds and FlotContinuous Integration, Fast Builds and Flot
Continuous Integration, Fast Builds and Flotmelbournepatterns
 
Command Pattern
Command PatternCommand Pattern
Command Patternmelbournepatterns
 

Recommended

The visitor design pattern
The visitor design patternThe visitor design pattern
The visitor design patternSamnang Chhun
 
An Introduction to
An Introduction to An Introduction to
An Introduction to melbournepatterns
 
State Pattern from GoF
State Pattern from GoFState Pattern from GoF
State Pattern from GoFmelbournepatterns
 
Iterator Pattern
Iterator PatternIterator Pattern
Iterator Patternmelbournepatterns
 
Iterator
IteratorIterator
Iteratormelbournepatterns
 
Concurrency Patterns
Concurrency PatternsConcurrency Patterns
Concurrency Patternsmelbournepatterns
 
Continuous Integration, Fast Builds and Flot
Continuous Integration, Fast Builds and FlotContinuous Integration, Fast Builds and Flot
Continuous Integration, Fast Builds and Flotmelbournepatterns
 
Command Pattern
Command PatternCommand Pattern
Command Patternmelbournepatterns
 
Code Contracts API In .Net
Code Contracts API In .NetCode Contracts API In .Net
Code Contracts API In .Netmelbournepatterns
 
LINQ/PLINQ
LINQ/PLINQLINQ/PLINQ
LINQ/PLINQmelbournepatterns
 
Gpu Cuda
Gpu CudaGpu Cuda
Gpu Cudamelbournepatterns
 
Facade Pattern
Facade PatternFacade Pattern
Facade Patternmelbournepatterns
 
Phani Kumar - Decorator Pattern
Phani Kumar - Decorator PatternPhani Kumar - Decorator Pattern
Phani Kumar - Decorator Patternmelbournepatterns
 
Composite Pattern
Composite PatternComposite Pattern
Composite Patternmelbournepatterns
 
Adapter Design Pattern
Adapter Design PatternAdapter Design Pattern
Adapter Design Patternmelbournepatterns
 
Prototype Design Pattern
Prototype Design PatternPrototype Design Pattern
Prototype Design Patternmelbournepatterns
 
Factory Method Design Pattern
Factory Method Design PatternFactory Method Design Pattern
Factory Method Design Patternmelbournepatterns
 
Abstract Factory Design Pattern
Abstract Factory Design PatternAbstract Factory Design Pattern
Abstract Factory Design Patternmelbournepatterns
 
A Little Lisp
A Little LispA Little Lisp
A Little Lispmelbournepatterns
 
State Pattern in Flex
State Pattern in FlexState Pattern in Flex
State Pattern in Flexmelbournepatterns
 
Active Object
Active ObjectActive Object
Active Objectmelbournepatterns
 
Extract Composite Talk Andy
Extract Composite Talk AndyExtract Composite Talk Andy
Extract Composite Talk Andymelbournepatterns
 
Selenium Interpreter
Selenium InterpreterSelenium Interpreter
Selenium Interpretermelbournepatterns
 
Move Accumulation To Collecting Parameter
Move Accumulation To Collecting ParameterMove Accumulation To Collecting Parameter
Move Accumulation To Collecting Parametermelbournepatterns
 
Mpg Dec07 Gian Lorenzetto
Mpg Dec07 Gian Lorenzetto Mpg Dec07 Gian Lorenzetto
Mpg Dec07 Gian Lorenzetto melbournepatterns
 
Mpg Feb08 Gian Lorenzetto
Mpg Feb08 Gian Lorenzetto Mpg Feb08 Gian Lorenzetto
Mpg Feb08 Gian Lorenzetto melbournepatterns
 
Dynamic Vs Static
Dynamic Vs StaticDynamic Vs Static
Dynamic Vs Staticmelbournepatterns
 
Command Pattern Geoff Burns 2006 Nov
Command Pattern Geoff Burns 2006 NovCommand Pattern Geoff Burns 2006 Nov
Command Pattern Geoff Burns 2006 Novmelbournepatterns
 
DBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor PresentationDBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor PresentationDropbox
 
MINDCTI Revenue Release Quarter One 2024
MINDCTI Revenue Release Quarter One 2024MINDCTI Revenue Release Quarter One 2024
MINDCTI Revenue Release Quarter One 2024MIND CTI
 

More Related Content

More from melbournepatterns

Phani Kumar - Decorator Pattern
Phani Kumar - Decorator PatternPhani Kumar - Decorator Pattern
Phani Kumar - Decorator Patternmelbournepatterns
 
Factory Method Design Pattern
Factory Method Design PatternFactory Method Design Pattern
Factory Method Design Patternmelbournepatterns
 
Abstract Factory Design Pattern
Abstract Factory Design PatternAbstract Factory Design Pattern
Abstract Factory Design Patternmelbournepatterns
 
Move Accumulation To Collecting Parameter
Move Accumulation To Collecting ParameterMove Accumulation To Collecting Parameter
Move Accumulation To Collecting Parametermelbournepatterns
 
Command Pattern Geoff Burns 2006 Nov
Command Pattern Geoff Burns 2006 NovCommand Pattern Geoff Burns 2006 Nov
Command Pattern Geoff Burns 2006 Novmelbournepatterns
 

More from melbournepatterns (20)

Code Contracts API In .Net
Code Contracts API In .NetCode Contracts API In .Net
Code Contracts API In .Net
 
LINQ/PLINQ
LINQ/PLINQLINQ/PLINQ
LINQ/PLINQ
 
Gpu Cuda
Gpu CudaGpu Cuda
Gpu Cuda
 
Facade Pattern
Facade PatternFacade Pattern
Facade Pattern
 
Phani Kumar - Decorator Pattern
Phani Kumar - Decorator PatternPhani Kumar - Decorator Pattern
Phani Kumar - Decorator Pattern
 
Composite Pattern
Composite PatternComposite Pattern
Composite Pattern
 
Adapter Design Pattern
Adapter Design PatternAdapter Design Pattern
Adapter Design Pattern
 
Prototype Design Pattern
Prototype Design PatternPrototype Design Pattern
Prototype Design Pattern
 
Factory Method Design Pattern
Factory Method Design PatternFactory Method Design Pattern
Factory Method Design Pattern
 
Abstract Factory Design Pattern
Abstract Factory Design PatternAbstract Factory Design Pattern
Abstract Factory Design Pattern
 
A Little Lisp
A Little LispA Little Lisp
A Little Lisp
 
State Pattern in Flex
State Pattern in FlexState Pattern in Flex
State Pattern in Flex
 
Active Object
Active ObjectActive Object
Active Object
 
Extract Composite Talk Andy
Extract Composite Talk AndyExtract Composite Talk Andy
Extract Composite Talk Andy
 
Selenium Interpreter
Selenium InterpreterSelenium Interpreter
Selenium Interpreter
 
Move Accumulation To Collecting Parameter
Move Accumulation To Collecting ParameterMove Accumulation To Collecting Parameter
Move Accumulation To Collecting Parameter
 
Mpg Dec07 Gian Lorenzetto
Mpg Dec07 Gian Lorenzetto Mpg Dec07 Gian Lorenzetto
Mpg Dec07 Gian Lorenzetto
 
Mpg Feb08 Gian Lorenzetto
Mpg Feb08 Gian Lorenzetto Mpg Feb08 Gian Lorenzetto
Mpg Feb08 Gian Lorenzetto
 
Dynamic Vs Static
Dynamic Vs StaticDynamic Vs Static
Dynamic Vs Static
 
Command Pattern Geoff Burns 2006 Nov
Command Pattern Geoff Burns 2006 NovCommand Pattern Geoff Burns 2006 Nov
Command Pattern Geoff Burns 2006 Nov
 

Recently uploaded

DBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor PresentationDBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor PresentationDropbox
 
MINDCTI Revenue Release Quarter One 2024
MINDCTI Revenue Release Quarter One 2024MINDCTI Revenue Release Quarter One 2024
MINDCTI Revenue Release Quarter One 2024MIND CTI
 
Corporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptxCorporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptxRustici Software
 
2024: Domino Containers - The Next Step. News from the Domino Container commu...
2024: Domino Containers - The Next Step. News from the Domino Container commu...2024: Domino Containers - The Next Step. News from the Domino Container commu...
2024: Domino Containers - The Next Step. News from the Domino Container commu...Martijn de Jong
 
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...Jeffrey Haguewood
 
AWS Community Day CPH - Three problems of Terraform
AWS Community Day CPH - Three problems of TerraformAWS Community Day CPH - Three problems of Terraform
AWS Community Day CPH - Three problems of TerraformAndrey Devyatkin
 
Boost Fertility New Invention Ups Success Rates.pdf
Boost Fertility New Invention Ups Success Rates.pdfBoost Fertility New Invention Ups Success Rates.pdf
Boost Fertility New Invention Ups Success Rates.pdfsudhanshuwaghmare1
 
Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...
Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...
Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...Miguel Araújo
 
Why Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire businessWhy Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire businesspanagenda
 
A Beginners Guide to Building a RAG App Using Open Source Milvus
A Beginners Guide to Building a RAG App Using Open Source MilvusA Beginners Guide to Building a RAG App Using Open Source Milvus
A Beginners Guide to Building a RAG App Using Open Source MilvusZilliz
 
Artificial Intelligence Chap.5 : Uncertainty
Artificial Intelligence Chap.5 : UncertaintyArtificial Intelligence Chap.5 : Uncertainty
Artificial Intelligence Chap.5 : UncertaintyKhushali Kathiriya
 
Navi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Navi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot ModelNavi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Navi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot ModelDeepika Singh
 
ICT role in 21st century education and its challenges
ICT role in 21st century education and its challengesICT role in 21st century education and its challenges
ICT role in 21st century education and its challengesrafiqahmad00786416
 
AXA XL - Insurer Innovation Award Americas 2024
AXA XL - Insurer Innovation Award Americas 2024AXA XL - Insurer Innovation Award Americas 2024
AXA XL - Insurer Innovation Award Americas 2024The Digital Insurer
 
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWEREMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWERMadyBayot
 
Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...
Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...
Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...Zilliz
 
Powerful Google developer tools for immediate impact! (2023-24 C)
Powerful Google developer tools for immediate impact! (2023-24 C)Powerful Google developer tools for immediate impact! (2023-24 C)
Powerful Google developer tools for immediate impact! (2023-24 C)wesley chun
 
Real Time Object Detection Using Open CV
Real Time Object Detection Using Open CVReal Time Object Detection Using Open CV
Real Time Object Detection Using Open CVKhem
 
Apidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, Adobe
Apidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, AdobeApidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, Adobe
Apidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, Adobeapidays
 

Recently uploaded (20)

DBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor PresentationDBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor Presentation
 
MINDCTI Revenue Release Quarter One 2024
MINDCTI Revenue Release Quarter One 2024MINDCTI Revenue Release Quarter One 2024
MINDCTI Revenue Release Quarter One 2024
 
Corporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptxCorporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptx
 
2024: Domino Containers - The Next Step. News from the Domino Container commu...
2024: Domino Containers - The Next Step. News from the Domino Container commu...2024: Domino Containers - The Next Step. News from the Domino Container commu...
2024: Domino Containers - The Next Step. News from the Domino Container commu...
 
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
 
AWS Community Day CPH - Three problems of Terraform
AWS Community Day CPH - Three problems of TerraformAWS Community Day CPH - Three problems of Terraform
AWS Community Day CPH - Three problems of Terraform
 
Boost Fertility New Invention Ups Success Rates.pdf
Boost Fertility New Invention Ups Success Rates.pdfBoost Fertility New Invention Ups Success Rates.pdf
Boost Fertility New Invention Ups Success Rates.pdf
 
Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...
Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...
Mastering MySQL Database Architecture: Deep Dive into MySQL Shell and MySQL R...
 
Why Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire businessWhy Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire business
 
A Beginners Guide to Building a RAG App Using Open Source Milvus
A Beginners Guide to Building a RAG App Using Open Source MilvusA Beginners Guide to Building a RAG App Using Open Source Milvus
A Beginners Guide to Building a RAG App Using Open Source Milvus
 
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
 
Artificial Intelligence Chap.5 : Uncertainty
Artificial Intelligence Chap.5 : UncertaintyArtificial Intelligence Chap.5 : Uncertainty
Artificial Intelligence Chap.5 : Uncertainty
 
Navi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Navi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot ModelNavi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Navi Mumbai Call Girls 🥰 8617370543 Service Offer VIP Hot Model
 
ICT role in 21st century education and its challenges
ICT role in 21st century education and its challengesICT role in 21st century education and its challenges
ICT role in 21st century education and its challenges
 
AXA XL - Insurer Innovation Award Americas 2024
AXA XL - Insurer Innovation Award Americas 2024AXA XL - Insurer Innovation Award Americas 2024
AXA XL - Insurer Innovation Award Americas 2024
 
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWEREMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
 
Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...
Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...
Emergent Methods: Multi-lingual narrative tracking in the news - real-time ex...
 
Powerful Google developer tools for immediate impact! (2023-24 C)
Powerful Google developer tools for immediate impact! (2023-24 C)Powerful Google developer tools for immediate impact! (2023-24 C)
Powerful Google developer tools for immediate impact! (2023-24 C)
 
Real Time Object Detection Using Open CV
Real Time Object Detection Using Open CVReal Time Object Detection Using Open CV
Real Time Object Detection Using Open CV
 
Apidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, Adobe
Apidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, AdobeApidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, Adobe
Apidays New York 2024 - Scaling API-first by Ian Reasor and Radu Cotescu, Adobe
 

Visitor Pattern By Steve Hayes

  • 1. Visitor Steve Hayes Cogent Consulting Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 2. The Problem Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 3. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 4. Show me everything in a consistent manner... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 5. Show me everything in a consistent manner... ... and send it to my friend via email Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 6. Show me everything in a consistent manner... ... and send it to my friend via email oh, and send it to her phone as well... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 7. Show me everything in a consistent manner... ... and send it to my friend via email oh, and send it to her phone as well... and print it..... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 8. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 9. Some analysis music please... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 10. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 11. Commonality is in the eye of the beholder Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 12. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 13. With a little casual application of polymorphism... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 14. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 15. Does this look bad to you? Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 16. The solution Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 17. Visitors Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 18. “Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates” -- GOF Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 19. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 20. A solution to a problem in a context Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 21. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 22. Headings, Details, ... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 23. and the Iterator Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 24. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 25. Let’s show it in code! Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 26. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 27. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 28. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 29. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 30. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 31. Time for visitors... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 32. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 33. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 34. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 35. Melbourne Pushes Boundaries The Wolves in the Wall Redhill Consulting Pty Ltd - Ruby on Rails Plugins Let's talk about tests, baby... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 36. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 37. Melbourne Pushes Boundaries Tim Colebatch Melbourne is experiencing its biggest growth surge since the 1960's The Wolves in the Wall 12.06 Redhill Consulting Pty Ltd - Ruby on Rails Plugins Here are some Ruby on Rails plugins we've developed... Let's talk about tests, baby... Some long babbling about test naming heuristics Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 38. Cool! Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 39. When? Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 40. “an object structure contains many classes of objects with differing interfaces, and you want to perform operations on these objects that depend on their concrete classes” Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 41. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 42. “many distinct and unrelated operations need to be performed on objects in an object structure, and you want to avoid ‘polluting’ their classes with these operations.Visitor lets you keep unrelated operations together by defining them in one class. When the object structure is shared by many applications, use Visitor to put operations in just those applications that need them” Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 43. Show me everything in a consistent manner... ... and send it to my friend via email oh, and send it to her phone as well... and print it..... Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 44. “the classes defining the object structure rarely change, but you often want to define new operations over the structure. Changing the object structure classes requires redefining the interface to all visitors, which is potentially costly. If the object structure classes change often, then it’s probably better to define the operations in those classes” Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 45. Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 46. Consequences Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 47. Visitor makes adding new operations easy Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 48. A visitor gathers related operations and separates unrelated ones Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 49. Adding new ConcreteElement classes is hard Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 50. Visitors can cross object hierarchies Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 51. Visitors can accumulate state Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 52. Visitors may compromise encapsulation Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.
  • 53. Discussion Copyright Cogent Consulting Pty Ltd (http://www.cogentconsulting.com.au) Licensed under a Creative Commons Attribution-Noncommercial 3.0 License.