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| -rw-r--r-- | doc/todo/dependency_types.mdwn | 46 |
1 files changed, 37 insertions, 9 deletions
diff --git a/doc/todo/dependency_types.mdwn b/doc/todo/dependency_types.mdwn index 97cff97c5..d31797f3d 100644 --- a/doc/todo/dependency_types.mdwn +++ b/doc/todo/dependency_types.mdwn @@ -239,6 +239,21 @@ sigh. >>> Hmm, I'm not seeing cycles be a problem, at least with the current >>> pagespec terms. --[[Joey]] +>>>> Oh, they're not with current pagespec terms. But this is really close to extending to handle +>>>> functional pagespecs, etc. And I think I'd like to think about that now. +>>>> +>>>> Having said that, I don't want to hold you up - you seem to be making progress. The best is +>>>> the enemy of the good, etc. etc. +>>>> +>>>> For my part, I'm imagining we have two more constructs in IkiWiki: +>>>> +>>>> * A map directive that actually wikilinks to the pages it links to, and +>>>> * A `match_sharedLink(pageX)` matching function that matches pageY if both pageX and pageY each have links to any same third page, pageZ. +>>>> +>>>> With those two constructs, one page changing might change the set of pages included in a map somewhere, which might then change the set of pages matched by some other pagespec, which might then... +>>>> +>>>> --[[Will]] + ---- ### Link dependencies @@ -313,16 +328,13 @@ can indirectly influence what pages a pagespec matches. > Trying to make a formal definition of this: (Note, I'm using the term sets rather than lists, but they're roughly equivalent) > -> * Let the *matching set* for a pagespec be the set of pages that the pagespec matches. -> * Let a *complete influence set* for a pagespec be the set of all pages whose alteration might change the matching set of that pagespec. -> * Let the *direct influence set* be the intersection of the matching set and the complete influence set. -> * Let the *indirect influence set* be the compliment of the direct influence set with respect to the complete influence set. +> * Let the *matching set* for a pagespec be the set of existing pages that the pagespec matches. +> * Let a *influence set* for a pagespec be the set of all pages, *p*, whose alteration might: +> * cause the pagespec to include or exclude a page other than *p*, or +> * cause the pagespec to exclude *p*. +> +>> \[Will snipped some stuff and edited the formal definition] > -> Is that a fair definition? I don't think it quite matches your examples below unfortunately. -> I was unsure if I should insert the word 'existing' in there in a few places. As it stands, these definitions could include sets of pages that don't exist, e.g. "*". -> The one I'm least sure of is the definition of the direct influence set. It feels like you want something -> like "the traditional set of things we thought about that could cause a pagespec to change", but that definition -> is not very formal and I suspect will lead to problems. Something like "The set of pages matched by the globs in the pagespec" might be closer? > --[[Will]] >> I appreciate the formalism! @@ -331,11 +343,24 @@ can indirectly influence what pages a pagespec matches. >> in the future, the existing dependency code will always test to see >> if it matches. So it will be in the maching set (or not) at that point. >> +>>> Hrm, I agree with you in general, but I think I can come up with nasty counter-examples. What about a pagespec +>>> 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. +>>> +>>> 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. +>> >> The problem with your definition of direct influence set seems to be >> that it doesn't allow `link()` and `title()` to have as an indirect >> influence, the page that matches. But I'm quite sure we need those. >> --[[Joey]] +>>> I see what you mean. Does the revised definition capture this effectively? +>>> The problem with this revised definition is that it still doesn't match your examples below. +>>> My revised definition will include pretty much all currently matching pages to be in the influence list +>>> because deletion of any of them would cause a change in which pages are matched - the removal problem. +>>> -- [[Will]] + #### Examples * The pagespec "created_before(foo)" has an influence list that contains foo. @@ -349,6 +374,9 @@ can indirectly influence what pages a pagespec matches. Avoiding including every page in the wiki into its influence list is very important! +>>> 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 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 |