add_depends: optimise influence calculation

[git.ikiwiki.info.git] / doc / todo / dependency_types.mdwn

diff --git a/doc/todo/dependency_types.mdwn b/doc/todo/dependency_types.mdwn
index cce5997e84d745a6d49a6ac9a7a7bdb340c3cb54..d9e68841d119bdba305da6d25f9304a2022ddf7f 100644 (file)
--- a/doc/todo/dependency_types.mdwn
+++ b/doc/todo/dependency_types.mdwn
@@ -278,6 +278,7 @@ sigh.
   that the page links to, which is just what link dependencies are
   triggered on.
 
+[[done]]
 ----
 
 ### the removal problem
@@ -501,6 +502,38 @@ to not link to done, the influence will do its job.
 
 Looks good!
 
+----
+
+Here is a case where this approach has some false positives.
+
+"bugs/* and link(patch)"
+
+This finds as influences all pages that link to patch, even
+if they are not under bugs/, and so can never match.
+
+To fix this, the influence calculation would need to consider boolean
+operators. Currently, this turns into roughly:
+
+`FailReason() & SuccessReason(patch)`
+
+Let's say that the glob instead returns a HardFailReason, which when
+ANDed with another object, drops their influences. (But when ORed, combines
+them.) Fixes the above, but does it always work?
+
+"(bugs/* or link(patch)) and backlink(index)" =>
+`( HardFailReason() | SuccessReason(page) ) & SuccessReason(index)`` =>
+`SuccessReason(page & SuccessReason(index)` =>
+SuccessReason(page, index) => right
+
+"(bugs/* and link(patch)) or backlink(index)" =>
+`( HardFailReason() & SuccessReason(page) ) | SuccessReason(index)`` =>
+`HardFailReason() | SuccessReason(index)` =>
+`SuccessReason(index)` => right
+
+"!bugs/* and link(patch)" =>
+`HardFailReason() | SuccessReason(bugs/foo)` =>  
+`HardFailReason()` => right
+
 #### High-level Calculation and Storage
 
 Naively calculating the full influence list for a pagespec requires trying