User:DavidJCobb/Template Sandbox/What Links Here experiment

It's possible, for any template, figure out what pages are calling it with certain parameters. For example, if I want to get a list of pages that are using a template ExampleTemplate with an unnamed parameter of Foobar, I can do this:

1. Modify ExampleTemplate so that it transcludes (calls) the (non-existent) template ExampleTemplate/Test:{{{1}}} (use the code {{ExampleTemplate/Text:{{{1}}}}}</code)
2. Go to the non-existent template <code>ExampleTemplate/Test:Foobar
3. Check "What links here" for that non-existent template

ExampleTemplate and all pages that call ExampleTemplate with the first unnamed parameter set to Foobar will be listed.

Demonstration

• Link Origin
• Link Target
• Link End

Link Origin calls the Link Target template with the first unnamed parameter set to Test. Link Target calls Link End. As a result, Link Target and Link Origin show up in Link End's What links here entry.

The demonstration can go even further. Link End doesn't even need to exist -- Link Target can just call a (non-existent) subpage of itself, like this: {{/Call:{{{1|}}}}}, and then we could check the What links here entry for any given subpage we want; e.x. we could check /Link Target/Call:Foobar to get a list of pages that call Link Target with the first unnamed paramter being set to Foobar.

Limits

• The What links here page will also show whatever template is using this trick. E.x. Link End's What links here entry shows Link Target.
• You have to use an article. Using an anchor/header (e.x. {{Link End#{{{1|}}}}}) won't work because you can't check What links here on individual sections/headers/anchors of a page.

Other subpages

• Actual Example - This example actually calls a non-existent subpage of itself, based on the first unnamed parameter you give it. I'm using this to test another WIP template.