Variable in MediaWiki for the current user

Question

In MediaWiki, you can use a variable ("Magic Word") such as

{{PAGENAME}}

or

{{REVISIONDAY}}

to get specific information related to the current page being viewed. Is there a similar variable (or perhaps a different way) to get the current user who is logged in to the wiki, i.e. something like

{{USERNAME}}

context: Trying to use the #ask query in Semantic MediaWiki to narrow the list of resulting pages to show those only the user has created or edited:

{{#ask: [[Case Reflection:+]] [[Contributing User::{{USERNAME}}]]
 | format=template
 | template=Case Reflection Form Summary
 | link=all
 | sort=Last Edited
 | order=DESC
 | default=You have no case reflections related to this Case Study.}}

Answer 1

There are a bunch of extensions for that such as GetUserName, MyVariables, UserInfo. The whole concept of showing usernames is incompatible with page caching though (you need to parse the page again every time someone looks at it) so generally not a good idea.