The short answer is yes. This is all done by "contextual" name evaluation. The +x processing is part of that, but there are a bunch of other substitutions that are very useful. So, from A+somename, if I want A+number, it is: {{_left+number}}. Theres stuff like _user, and _param (where param is the name of a query parameter).
See contextual names. We don't technically have any syntax for the "nesting" card (which you're calling the host), but we do have handling for the name parents (_left and _right). Since the most common case is for the left name parent to nest the name child, you have the syntax you need there.
Gerry, I think everything you said is spot on except for _param. I don't think that's actually a thing; pretty sure it's not a "blessed" part of the nest API.
I misremembered this little piece of code:
when /^_/
custom = args[:params] ? args[:params][part] : nil
custom ? CGI.escapeHTML(custom) : part #why are we escaping HTML here?
The params are not query params, but view params. I imagine that is used for things like keyword searches where the custom view arg is from code, not inclusion syntax.
I don't think that code is used. Almost certainly not from nests.
We should probably remove it if it isn't used now. I'm sure you probably know that's from Smartname.
ya. and ya.
Ok great! This is what I was looking for contextual names, and the _L, _R, _LL, _LR, _LLL part is particularly interesting.
Yeah, like car and cdr in lisp, or cddr and caddddr. Don't stress out the way-back machine on those references.