Example. Template:Potd/2011-01-03 doesn't exist yet.

{{Potd/2011-01-03|#defaulttext=Create this template}}

would return "Create this template", which would be a redlink for Template:Potd/2011-01-03

When Template:Potd/2011-01-03 was created, {{Potd/2011-01-03|#defaulttext=Create this template}} would ignore the #defaulttext setting, and just transclude it.

Uses: Mainly in setup pages for the main pages of sites, where it's likely that things will be getting set up in a way that

Reasons: #ifexist is a high cost parser function. This would (hopefully) be a very low cost function, since the server has to know if the template exists anyway, as part of the attempt to transclude.

This would allow vastly improved user interfaces in these specific cases.

Version: unspecified
Severity: enhancement