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authorJoey Hess <joey@gnu.kitenet.net>2009-10-08 13:54:51 -0400
committerJoey Hess <joey@gnu.kitenet.net>2009-10-08 13:55:10 -0400
commit3baf6980aa5725b647bf72452be2c05db1ad0bff (patch)
tree0feed8332f4b1925ef302a5f7ab2d096eaf55dfb
parent79f3e32ea7adf3e5adbef0a8c9c68cd32a67cac4 (diff)
update
-rw-r--r--doc/todo/dependency_types.mdwn55
1 files changed, 53 insertions, 2 deletions
diff --git a/doc/todo/dependency_types.mdwn b/doc/todo/dependency_types.mdwn
index d31797f3d..cce5997e8 100644
--- a/doc/todo/dependency_types.mdwn
+++ b/doc/todo/dependency_types.mdwn
@@ -254,6 +254,14 @@ sigh.
>>>>
>>>> --[[Will]]
+>>>>> I think that should be supported by [[bugs/transitive_dependencies]].
+>>>>> At least in the current implementation, which considers each page
+>>>>> that is rendered to be changed, and rebuilds pages that are dependent
+>>>>> on it, in a loop. An alternate implementation, which could be faster,
+>>>>> is to construct a directed graph and traverse it just once. Sounds
+>>>>> like that would probably not support what you want to do.
+>>>>> --[[Joey]]
+
----
### Link dependencies
@@ -347,6 +355,13 @@ can indirectly influence what pages a pagespec matches.
>>> of "!backlink(bogus)" where the page bogus doesn't exist? In this case, the page 'bogus' needs to be in the influence
>>> set even though it doesn't exist.
>>>
+>>>> I think you're right, this is a case that the current code is not
+>>>> handling. Actually, I made all the pagespecs return influences
+>>>> even if the influence was not present or did not match. But, it
+>>>> currently only records influences as dependencies when a pagespec
+>>>> successfully matches. Now I'm sure that is wrong, and I've removed
+>>>> that false optimisation. I've updated some of the below. --[[Joey]]
+>>>
>>> Also, I would really like the formalism to include the whole dependency system, not just any additions to it. That will make
>>> the whole thing much easier to reason about.
>>
@@ -364,7 +379,8 @@ can indirectly influence what pages a pagespec matches.
#### Examples
* The pagespec "created_before(foo)" has an influence list that contains foo.
- The removal or (re)creation of foo changes what pages match it.
+ The removal or (re)creation of foo changes what pages match it. Note that
+ this is true even if the pagespec currently fails to match.
* The pagespec "foo" has an empty influence list. This is because a
modification/creation/removal of foo directly changes what the pagespec
@@ -377,13 +393,27 @@ can indirectly influence what pages a pagespec matches.
>>> So, why don't the above influence lists contain the currently matched pages?
>>> Don't you need this to handle the removal problem? -- [[Will]]
+>>>> The removal problem is slightly confusingly named, since it does not
+>>>> affect pages that were matched by a glob and have been removed. Such
+>>>> pages can be handled without being influences, because ikiwiki knows
+>>>> they have been removed, and so can still match them against the
+>>>> pagespec, and see they used to match; and thus knows that the
+>>>> dependency has triggered.
+>>>>
+>>>> Maybe the thing to do is consider this an optimisation, where such
+>>>> pages are influences, but ikiwiki is able to implicitly find them,
+>>>> so they do not need to be explicitly stored. --[[Joey]]
+
* The pagespec "title(foo)" has an influence list that contains every page
that currently matches it. A change to any matching page can change its
title, making it not match any more, and so the list is needed due to the
- removal problem.
+ removal problem. A page that does not have a matching title is not an
+ influence, because modifying the page to change its title directly
+ changes what the pagespec matches.
* The pagespec "backlink(index)" has an influence list
that contains index (because a change to index changes the backlinks).
+ Note that this is true even if the backlink currently fails.
* The pagespec "link(done)" has an influence list that
contains every page that it matches. A change to any matching page can
@@ -450,6 +480,27 @@ successful match, we get the right result.
> `or` short-circuits too, but the implementation correctly uses `|`,
> which I assume is what you meant. --[[smcv]]
+>> Er, yeah. --[[Joey]]
+
+----
+
+What about: "!link(done)"
+
+Specifically, I want to make sure it works now that I've changed
+`match_link` to only return a page as an influence if it *does*
+link to done.
+
+So, when matching against page P, that does not link to done,
+there are no influences, and the pagespec matches. If P is later
+changed to add a link to done, then the dependency resolver will directly
+notice that.
+
+When matching against page P, that does link to done, P
+is an influence, and the pagespec does not match. If P is later changed
+to not link to done, the influence will do its job.
+
+Looks good!
+
#### High-level Calculation and Storage
Naively calculating the full influence list for a pagespec requires trying