Jump to content
Main menu
Main menu
move to sidebar
hide
Navigation
Main page
Contents
Current events
Random article
About Wikipedia
Contact us
Contribute
Help
Learn to edit
Community portal
Recent changes
Upload file
Special pages
Search
Search
Appearance
Donate
Create account
Log in
Personal tools
Donate
Create account
Log in
Pages for logged out editors
learn more
Contributions
Talk
Programming practice
Add languages
Add links
Article
Talk
English
Read
Edit
View history
Tools
Tools
move to sidebar
hide
Actions
Read
Edit
View history
General
What links here
Related changes
Upload file
Permanent link
Page information
Cite this page
Get shortened URL
Download QR code
Print/export
Download as PDF
Printable version
Appearance
move to sidebar
hide
From Wikipedia, the free encyclopedia
Redirect to:
Software design pattern
Search
Search
Programming practice
Add languages
Add topic
