[ic] Open and 'run' a page from within another page?

[marc.brevoort]

Hello group,

Back when I used PHP, it was possible to load a page from another
one by telling it require(pagename) require_once(pagename).

Interchange allows for something similar using the tags 
include(filename) or file (filename). However I've run into a
problem here.

* If I use the file tag (with interpolate=1) to include a file, 
perl tags in the included page are properly executed, but
variables such as __UI_BASE__ are untouched.

* If I use the include tag, (with interpolate=1), __UI_BASE__ is
properly interpolated, but now the perl tags stop giving any
output. According to the documentation, the include tag should 
interpolate all tags and variables.

(The error log does not show any errors as long as I don't
attempt to use the header template, I suspect the perl tags
are blocked by Safe but I'm not sure).

How can I run a page from within another page, and make it act
in the same way it would when running stand-alone?

Any tips, anyone?

Regards,

Marc Brevoort