great many things don't care about the modification case, and often cause
unnecessary page rebuilds:
-* meta only cares if the pages are added or removed. Content change does
+* map only cares if the pages are added or removed. Content change does
not matter (unless show=title is used).
* brokenlinks, orphans, pagecount, ditto (generally)
* inline in archive mode cares about page title, author changing, but
I propose the following. --[[Joey]]
-* Add a second type of dependency, call it an "contentless dependency".
+* Add a second type of dependency, call it an "presence dependency".
* `add_depends` defaults to adding a regular ("full") dependency, as
before. (So nothing breaks.)
-* `add_depends($page, $spec, content => 0)` adds an contentless dependency.
-* `refresh` only looks at added/removed pages when resolving contentless
+* `add_depends($page, $spec, presence => 0)` adds an presence dependency.
+* `refresh` only looks at added/removed pages when resolving presence
dependencies.
This seems straightforwardly doable. I'd like [[Will]]'s feedback on it, if
Then I found some problems:
-* pagestats is often used with a pagespec that uses `tagged()`.
- A pure contentless dependency does not work for that, it needs to look
- at link info.
-* orphans and brokenlinks cannot use contentless dependencies because they
- need to update when links change.
* Something simple like pagecount, that seems like it could use a
- contentless dependency, can have a pagespec that uses metadata, like
+ presence dependency, can have a pagespec that uses metadata, like
`author()` or `copyright()`.
+* pagestats, orphans and brokenlinks cannot use presence dependencies
+ because they need to update when links change.
-Now I'm thinking about having a contentless dependency look at page
+Now I'm thinking about having a special dependency look at page
metadata, and fire if the metadata changes. And it seems links should
either be included in that, or there should be a way to make a dependency
that fires when a page's links change. (And what about backlinks?)
It's easy to see when a page's links change, since there is `%oldlinks`.
To see when metadata is changed is harder, since it's stored in the
-pagestate by the meta plugin.
+pagestate by the meta plugin. Also, there are many different types of
+metadata, that would need to be matched with the pagespecs somehow.
+
+Quick alternative: Make add_depends look at the pagespec. Ie, if it
+is a simple page name, or a glob, we know a presence dependency
+can be valid. If's more complex, convert the dependency from
+presence to full.
+
+There is a lot to dislike about this method. Its parsing of the pagespec,
+as currently implemented, does not let plugins add new types of pagespecs
+that only care about presence. Its pagespec parsing is also subject to
+false negatives (though these should be somewhat rare, and no false
+positives). Still, it does work, and it makes things like simple maps and
+pagecounts much more efficient.
+
+----
+
+### Link dependencies
+
+* `add_depends($page, $spec, links => 1, presence => 1)`
+ adds a links + presence dependency.
+* `refresh` only rebuilds a page with a links dependency if
+ pages matched by the pagespec gain or lose links. (What the link
+ actually points to may change independent of this, due to changes
+ elsewhere, without it firing.)
+* So, brokenlinks can fire whenever any links in any of the
+ pages it's tracking change, or when pages are added or
+ removed.
+* To determine if a pagespec is valid to be used with a links dependency,
+ use the same set that are valid for presence dependencies. But also
+ allow `backlinks()` to be used in it, since that matches pages
+ that the page links to, which is just what link dependencies are
+ triggered on.
-(Alternative: Make add_depends look at the pagespec. Ie, if it is a simple
-page name, or a glob, we know a contentless dependency can be valid.
-If's more complex, convert the dependency from contentless to full. Finding
-a non-ad-hoc, non-sucky way to do that could be hard.)
+----
+
+### the removal problem
+
+So far I have not addressed fixing the removal problem (which Will
+discusses above).
+
+Summary of problem: A has a dependency on a pagespec such as
+"bugs/* and !link(done)". B currently matches. Then B is updated,
+in a way that makes A's dependency not match it (ie, it links to done).
+Now A is not updated, because ikiwiki does not realize that it
+depended on B before.
+
+This was worked around to fix [[bugs/inline_page_not_updated_on_removal]]
+by inline and map adding explicit dependencies on each page that appears
+on them. Then a change to B triggers the explicit dep. While this works,
+it's 1) ugly 2) probably not implemented by all plugins that could
+be affected by this problem (ie, linkmap) and 3) is most of the reason why
+we grew the complication of `depends_simple`.
+
+One way to fix this is to include with each dependency, a list of pages
+that currently match it. If the list changes, the dependency is triggered.
+
+Should be doable, but seems to involve a more work than
+currently. Consider that a dependency on "bugs/*" currently
+is triggered by just checking until *one* page is found to match it.
+But to store the list, *every* page would have to be tried against it.
+Unless the list can somehow be intelligently updated, looking at only the
+changed pages.