X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/83826b39cfefd2588da09ca427d48f11a92ea8c0..b9ba68208ebdb250dc4d4f8866cb834f5bd8764c:/doc/todo/tracking_bugs_with_dependencies.mdwn?ds=inline

diff --git a/doc/todo/tracking_bugs_with_dependencies.mdwn b/doc/todo/tracking_bugs_with_dependencies.mdwn
index 6e55e46af..3a761731b 100644
--- a/doc/todo/tracking_bugs_with_dependencies.mdwn
+++ b/doc/todo/tracking_bugs_with_dependencies.mdwn
@@ -257,6 +257,9 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 >>>> To fix that I'll need to pass a reference to that array into pagespec_makeperl.
 >>>> I think I can then do the same thing to $params{specFuncs}.  -- [[Will]]
 
+>>>>> You're right -- I did not think the recursive case through.
+>>>>> --[[Joey]] 
+
 > * Seems that the only reason `match_glob` has to check for `~` is
 >   because when a named spec appears in a pagespec, it is translated
 >   to `match_glob("~foo")`. If, instead, `pagespec_makeperl` checked
@@ -283,13 +286,18 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 
 >>>> and
 
-    define(aStar, a*) and link(aStar)
+    define(aStar, a*) and link(~aStar)
 
 >>>> In the first case, we want the pagespec to match any page that links to a page matching the glob.
 >>>> In the second case, we want the pagespec to match any page that links to a page matching the named spec.
 >>>> match_link() was already doing existential part.  The patches to this code were simply to remove the `lc()`
 >>>> call from the named pagespec name.  Can that `lc` be removed entirely? -- [[Will]]
 
+>>>>> I think we could get rid of it. `bestlink` will lc it itself
+>>>>> if the uppercase version does not exist; `match_glob` matches
+>>>>> insensitively.
+>>>>> --[[Joey]] 
+
 > * Generally, the need to modify `match_*` functions so that they
 >   check for and handle named pagespecs seems suboptimal, if
 >   only because there might be others people may want to use named
@@ -310,6 +318,33 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 >>>> Yes, and it can do that in just three lines of code.  But if we automatically check for named pagespecs all the time we
 >>>> potentially break any matching function that doesn't accept pages, or wants to use multiple arguments.
 
+>>>>> 3 lines of code, plus the functions called become part of the API,
+>>>>> don't forget about that..
+>>>>>
+>>>>> Yes, I think that is the tradeoff, the question is whether to export
+>>>>> the additional complexity needed for that flexability.
+>>>>>
+>>>>> I'd be suprised if multiple argument pagespecs become necessary..
+>>>>> with the exception of this patch there has been no need for them yet.
+>>>>>
+>>>>> There are lots of pagespecs that take data other than pages,
+>>>>> indeed, that's really the common case. So far, none of them 
+>>>>> seem likely to take data that starts with a `~`. Perhaps
+>>>>> the thing to do would be to check if `~foo` is a known,
+>>>>> named pagespec, and if not, just pass it through unchanged.
+>>>>> Then there's little room for ambiguity, and this also allows
+>>>>> pagespecs like `glob(~foo*)` to match the literal page `~foo`.
+>>>>> (It will make pagespec_merge even harder tho.. see below.)
+>>>>> --[[Joey]] 
+
+>>>>>> I've already used multi-argument pagespec match functions in
+>>>>>> my data plugin.  It is used for having different types of links.  If
+>>>>>> you want to have multiple types of links, then the match function
+>>>>>> for them needs to take both the link name and the link type.
+>>>>>> I'm trying to think of a way we could have both - automatically
+>>>>>> handle the existential case unless the function indicates somehow
+>>>>>> that it'll do it itself.  Any ideas?  -- [[Will]]
+
 > * I need to check if your trick to avoid infinite recursion
 >   works if there are two named specs that recursively
 >   call one-another. I suspect it does, but will test this
@@ -339,6 +374,40 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 
 >>>>> Looks like its bracketed in the code anyway... -- [[Will]]
 
+>>>> Perhaps the thing to do is to have a `clear_defines()`
+>>>> function, then merging `A` and `B` yields `(A) or (clear_defines() and (B))`
+>>>> That would deal with both the cases where `A` and `B` differently
+>>>> define `~foo` as well as with the case where `A` defines `~foo` while
+>>>> `B` uses it to refer to a literal page.
+>>>> --[[Joey]]
+
+>>>>> I don't think this will work with the new patch, and I don't think it was needed with the old one.
+>>>>> Under the old patch, pagespec_makeperl() generated a string of unevaluated, self-contained, perl
+>>>>> code.  When a new named pagespec was defined, a recursive call was made to get the perl code
+>>>>> for the pagespec, and then that code was used to add something like `$params{specFuncs}->{name} = sub {recursive code} and `
+>>>>> to the result of the calling function.  This means that at pagespec testing time, when this code is executed, the
+>>>>> specFuncs hash is built up as the pagespec is checked.  In the case of the 'or' used above, later redefinitions of
+>>>>> a named pagespec would have redefined the specFunc at the right time.  It should have just worked.  However...
+
+>>>>> Since my original patch, you started using closures for security reasons (and I can see the case for that).  Unfortunately this
+>>>>> means that the generated perl code is no longer self-contained - it needs to be evaluated in the same closure it was generated
+>>>>> so that it has access to the data array.  To make this work with the recursive call I had two options: a) make the data array a
+>>>>> reference that I pass around through the pagespec_makeperl() functions and have available when the code is finally evaluated
+>>>>> in pagespec_translate(), or b) make sure that each pagespec is evaluated in its correct closure and a perl function is returned, not a
+>>>>> string containing unevaluated perl code.
+
+>>>>> I went with option b).  I did it in such a way that the hash of specfuncs is built up at translation time, not at execution time.  This
+>>>>> means that with the new code you can call specfuncs that get defined out of order:
+
+    ~test and define(~test, blah)
+
+>>>>> but it also means that using a simple 'or' to join two pagespecs wont work.  If you do something like this:
+
+    ~test and define(~test, foo) and define(~test, baz)
+
+>>>>> then the last definition (baz) takes precedence.
+>>>>> In the process of writing this I think I've come up with a way to change this back the way it was, still using closures. -- [[Will]]
+
 >>  Secondly, it seems that there are two types of dependency, and ikiwiki
 >>  currently only handles one of them.  The first type is "Rebuild this
 >>  page when any of these other pages changes" - ikiwiki handles this.
@@ -385,11 +454,25 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 >>>>> are inlined, the previous type handles a change in the content of any of those pages.  Shortcut does not need this type of
 >>>>> dependency.  Most of the places that use `add_depends()` seem to need this type of dependency rather than the first type.
 
+>>>>>> Note that inline and map currently achieve the second type of dependency by
+>>>>>> explicitly calling `add_depends` for each page the displayed.
+>>>>>> If any of those pages are removed, the regular pagespec would not
+>>>>>> match them -- since they're gone. However, the explicit dependency
+>>>>>> on them does cause them to match. It's an ugly corner I'd like to
+>>>>>> get rid of. --[[Joey]]
+
 >>>>> Implementation Details:  The first type of dependency can be handled very similarly to the current
 >>>>> dependency system.  You just need to keep a list of pages that the content depends upon.  You could
 >>>>> keep that list as a pagespec, but if you do this you might want to check that the pagespec doesn't change,
 >>>>> possibly by adding a dependency of the second type along with the dependency of the first type.
 
+>>>>>> An example of the current system not tracking enough data is 
+>>>>>> where A inlines B which inlines C. A change to C will cause B to
+>>>>>> rebuild, but A will not "notice" that B has implicitly changed.
+>>>>>> That example suggests it might be fixable without explicitly storing
+>>>>>> data, by causing a rebuild of B to be treated as a change to B.
+>>>>>> --[[Joey]] 
+
 >>>>> The second type of dependency is a little more tricky.  For each page, we'd need a list of pagespecs that
 >>>>> the page depended on, and for each pagespec you'd want to store the list of pages that currently match it.
 >>>>> On refresh, you'd need to check each pagespec to see if the set of pages that match it has changed, and if
@@ -411,6 +494,19 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 
 Patch updated to use closures rather than inline generated code for named pagespecs.  Also includes some new use of ErrorReason where appropriate. -- [[Will]]
 
+> * Perl really doesn't need forward declarations, honest!
+
+>> It complained (warning, not error) when I didn't use the forward declaration. :(
+
+> * I have doubts about memoizing the anonymous sub created by
+>   `pagespec_translate`.
+
+>> This is there explicitly to make sure that runtime is polynomial and not exponential.
+
+> * Think where you wrote `+{}` you can just write `{}`
+
+>> Possibly :) -- [[Will]]
+
 ----
 
     diff --git a/IkiWiki.pm b/IkiWiki.pm