As Markus suggests in bug 13151, this is material for an extension, ie not for SMW itself.

Why is this wontfixed? Can't we just turn it into extension request?

Sure. I changed component from SMW to "other".

For reference, this bug report is closely related:

https://bugzilla.wikimedia.org/show_bug.cgi?id=30628

The relevant information from that is that display of metaproperties should be optional, and individually controlled, within the extension. The reason for that is that there are probably going to be a lot of them eventually, and many of them may not be relevant for every wiki's needs.

In the future, that will become more clear. For all I know it'll end up being considered essential everywhere for everything. Until then, it'd be good to make sure the display of metaproperties is optional, and preferably individually controlled, according to the preferences of the wiki owner.

I entered a "blocker" bug report for the requested page creation date property:

https://bugzilla.wikimedia.org/show_bug.cgi?id=30784

I believe it needs to be in SMW core in order for progress to be made on the bug requesting the ability to check for duplicates:

https://bugzilla.wikimedia.org/show_bug.cgi?id=30537

While helping someone with their question about querying for categories in #semantic-mediawiki, I told the asker that it could only be done if the category were stored as a property. "Saruman" corrected me to say that category information can in fact be obtained in queries simply by querying for ?Category like this:

{{#ask: [[somepage]] | ?Category}}

This works even though Category is not a built-in semantic property like Modification date is. I was unable to find any documentation for this, but he explained:

<Saruman> badon: category is the SMW translation of the semantic "class" object
<Saruman> see http://semantic-mediawiki.org/wiki/Help:Displaying_information#Printing_categories

I asked if there were other things in the list contained in this bug report that can be obtained via queries, despite not being built in properties, and if there is documentation of it. He said:

[14:45:13] <Saruman> badon: I once wrote a primer on semantics that explained that, but some people wanted that deleted from the SMW site

So, there may be parts of this bug report that are currently doable, but have had their documentation deleted. I don't understand what an "SMW translation" is. If someone knows, and can explain that, I can research it further.

If Saruman's documentation has survived somewhere, please make it accessible here:

https://www.mediawiki.org/wiki/User:Badon/Extension:Semantic_MediaWiki/Manual

leo_wallentin wrote:

In case someone else needs this, I wrote a small extension adding some meta properties ('Article author', 'Article creator', 'Revision ID' and 'Number of page views'): http://www.mediawiki.org/wiki/Extension:SemanticExtraSpecialProperties

What's the difference between Article author and Article creator? Is "creator" the first editor, and "author" all editors?

leo_wallentin wrote:

Exactly. Any ideas on how to make that more clear? Maybe 'first author' instead?

I called them "Page creator" (singular), and "Page editors" (plural) in my list here:

http://www.mediawiki.org/wiki/User:Badon/Extension:Semantic_MediaWiki/Manual#Needed_special_properties

The singular and plural difference may be enough, but I think "editors" is more clear than "authors" since the word "authors" is usually associated with only one or just a few people, while "editors" is understood in a wiki context to mean unlimited numbers of people.

There is always only one creator for a wiki page, so I think it is more clear than "first author". Since the word "author" already means "one author", it doesn't help to clarify things by changing it to "first author".

So, in short, I think "creator" and "editors" are the right words to use. I would not use "Article" because some wikis use mediawiki pages for something other than an article. "Page" is sufficiently broad, but maybe it would be better to follow the convention being used in this bug:

https://bugzilla.wikimedia.org/show_bug.cgi?id=32165

There, instead of using my suggested "Page creation date" and "Page modification date", it was decided to use "_CDAT" and "_MDAT", which are the internal SMW representations for those properties. Following that convention may help make your code a candidate for inclusion in a future version of SMW.