X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/5b2945cc921b222b07415ebea0c0d699f2a9dace..0e72550870ed51aa6aee57e08f63edf0b07befc0:/doc/todo/tracking_bugs_with_dependencies.mdwn diff --git a/doc/todo/tracking_bugs_with_dependencies.mdwn b/doc/todo/tracking_bugs_with_dependencies.mdwn index 707790a75..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 @@ -331,12 +366,48 @@ account all comments above (which doesn't mean it is above reproach :) ). --[[W >>> it shouldn't (but I haven't verified that really happens). >>> That could certianly be a show-stopper. --[[Joey]] +>>>> I think this can happen in the new closure based code. I don't think this could happen in the old code. -- [[Will]] + >>>> Even if that works, this is a good argument for having a syntactic difference between named pagespecs and normal pages. >>>> If you're joining two pagespecs with 'or', you don't want a named pagespec in the first part overriding a page name in the >>>> second part. Oh, and I assume 'or' has the right operator precedence that "a and b or c" is "(a and b) or c", and not "a and (b or c)" -- [[Will]] >>>>> 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. @@ -383,11 +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 @@ -409,6 +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