create site.pages with globs

[karthik2804]

Allows to add optional frontmatter to templates to allow for reading only files specified by globs instead of all the files in the content folder.

---
read_pages_glob = "events/*.md"
---

[itowlson]

The authoring experience here relies on the assumption that each template is interested in only one glob. Consider a page with both an "upcoming events" and a "featured articles" section. Is the expectation that such a page would get broken down into three templates, one for each "area of interest" section and one for the overall page? Is that a reasonable way for an author/designer to approach such a page? Is that how we've traditionally done things?

[karthik2804]

Only the Top template controls what is passed down to its children, we could possibly switch to globwalk and support specifying multiple globs. thoughts @itowlson?

or even something like where the read_pages_glob becomes Vec<String> without switching libraries

read_pages_glob = ["events/*.md",  "changelog/*.md"]

[itowlson]

I can't really comment on functionality, but it looks like this is pretty much existing code with a different file picker strapped on the front, so I'm sure that's fine - my comments are style only.

[itowlson]

Sorry missed your reply to the authoring/scope question. That sounds a bit unlovely - naively, it would be nice for each loop to only have to inspect the things in its glob - but if that's how we have to do it then that's how we have to do it - I'll take your advice on what's practical.

[karthik2804]

Unfortunately the way things are laid out as is we can't make the inspecting thing per loop without it breaking. I think the array of strings is the easiest thing to do in a non breaking manner.

[itowlson]

I'm afraid I still have significant stylistic concerns, but I appreciate we need this quickly and I trust you on the functionality, so I'm okay with revisiting those in a follow-up PR if that works better for you. Thanks for the quick turnaround on this!

[itowlson]

Thank you. The new functions really help.