Comment on potential bug

[www/ikiwiki.git] / 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 ba653fdcc335fac66fe01ae21ec77d1eac698b86..464f68363eb35ab4c11d2ef6f0076cbdf0c3a711 100644 (file)
--- a/doc/todo/tracking_bugs_with_dependencies.mdwn
+++ b/doc/todo/tracking_bugs_with_dependencies.mdwn
@@ -11,6 +11,8 @@ I like the idea of [[tips/integrated_issue_tracking_with_ikiwiki]], and I do so
 >
 >> I thought about this briefly, and got about that far.. glad you got
 >> further. :-) --[[Joey]]
 >
 >> I thought about this briefly, and got about that far.. glad you got
 >> further. :-) --[[Joey]]

+
+>> Or, one [[!taglink could_also_refer|pagespec_in_DL_style]] to the language of [[!wikipedia description logics]]: their formulas actually define classes of objects through quantified relations to other classes. --Ivan Z.

 > 
 > Another option would be go with a more functional syntax.  The concept here would
 > be to allow a pagespec to appear in a 'pagespec function' anywhere a page can.  e.g.
 > 
 > Another option would be go with a more functional syntax.  The concept here would
 > be to allow a pagespec to appear in a 'pagespec function' anywhere a page can.  e.g.


@@ -58,6 +60,7 @@ I like the idea of [[tips/integrated_issue_tracking_with_ikiwiki]], and I do so
 
 >> So, equivilant example: `define(bugs, bugs/* and !*/Discussion) and define(openbugs, bugs and !link(done)) and openbugs and !link(openbugs)`
 >> 
 
 >> So, equivilant example: `define(bugs, bugs/* and !*/Discussion) and define(openbugs, bugs and !link(done)) and openbugs and !link(openbugs)`
 >> 

+

 >> Re recursion, it is avoided.. but building a pagespec that is O(N^X) where N is the
 >> number of pages in the wiki is not avoided. Probably need to add DOS prevention.
 >>  --[[Joey]]
 >> Re recursion, it is avoided.. but building a pagespec that is O(N^X) where N is the
 >> number of pages in the wiki is not avoided. Probably need to add DOS prevention.
 >>  --[[Joey]]


@@ -67,13 +70,15 @@ I like the idea of [[tips/integrated_issue_tracking_with_ikiwiki]], and I do so
 
 >>>> Yeah, guess that'd work. :-)
 
 
 >>>> Yeah, guess that'd work. :-)
 

-> One quick further thought.  All the above discussion assumes that 'dependency' is the
+> <a id="another_kind_of_links" />One quick further thought.  All the above discussion assumes that 'dependency' is the

 > same as 'links to', which is not really true.  For example, you'd like to be able to say
 > "This bug does not depend upon [ [ link to other bug ] ]" and not have a dependency.
 > Without having different types of links, I don't see how this would be possible.
 >
 > -- [[Will]]
 
 > same as 'links to', which is not really true.  For example, you'd like to be able to say
 > "This bug does not depend upon [ [ link to other bug ] ]" and not have a dependency.
 > Without having different types of links, I don't see how this would be possible.
 >
 > -- [[Will]]
 

+>> I saw that this issue is targeted at by the work on [[structured page data#another_kind_of_links]]. --Ivan Z.
+

 Okie - I've had a quick attempt at this.  Initial patch attached.  This one doesn't quite work.
 And there is still a lot of debugging stuff in there.
 
 Okie - I've had a quick attempt at this.  Initial patch attached.  This one doesn't quite work.
 And there is still a lot of debugging stuff in there.
 


@@ -191,23 +196,39 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 > Very belated code review of last version of the patch:
 > 
 > * `is_globlist` is no longer needed
 > Very belated code review of last version of the patch:
 > 
 > * `is_globlist` is no longer needed

-> * `pagespec_translate` is already memoized, so the explicit call
->   to memoize when handling a define seems unnecessary?
+
+>> Good :)
+

 > * I don't understand why the pagespec match regexp is changed
 >   from having flags `igx` to `ixgs`. Don't see why you
 >   want `.` to match '\n` in it, and don't see any `.` in the regexp 
 >   anyway?
 > * I don't understand why the pagespec match regexp is changed
 >   from having flags `igx` to `ixgs`. Don't see why you
 >   want `.` to match '\n` in it, and don't see any `.` in the regexp 
 >   anyway?

+
+>> Because you have to define all the named pagespecs in the pagespec, you sometimes end up with very long pagespecs.  I found it useful to split them over multiple lines.  That didn't work at one point and I added the 's' to make it work.  I may have further altered the regex since then to make the 's' redundant.  Remove it and see if multi-line pagespecs still work. :)
+

 > * Some changes of `@_` to `%params` in `pagespec_makeperl` do not
 >   make sense to me. I don't see where \%params is defined and populated,
 >   except with `\$params{specFunc}`.
 > * Some changes of `@_` to `%params` in `pagespec_makeperl` do not
 >   make sense to me. I don't see where \%params is defined and populated,
 >   except with `\$params{specFunc}`.

+
+>> I'm not a perl hacker.  This was a mighty battle for me to get going.  There is probably some battlefield carnage from my early struggles learning perl left here.
+>> Part of this is that @_ / @params already existed as a way of passing in extra parameters.  I didn't want to pollute that top level namespace - just at my own parameter (a hash) which contained the data I needed.
+

 > * 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
 >   for named specs, it could convert them into `check_named_spec("foo")`
 >   and avoid that ugliness.
 > * 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
 >   for named specs, it could convert them into `check_named_spec("foo")`
 >   and avoid that ugliness.

+
+>> Yeah - I wanted to make named specs syntactically different on my first pass.  You are right in that this could be made a fallback - named specs always override pagenames.
+

 > * The changes to `match_link` seem either unecessary, or incomplete.
 >   Shouldn't it check for named specs and call
 >   `check_named_spec_existential`?
 > * The changes to `match_link` seem either unecessary, or incomplete.
 >   Shouldn't it check for named specs and call
 >   `check_named_spec_existential`?

+
+>>  An earlier version did.  Then I realised it wasn't actually needed in that case - match_link() already included a loop that was like a type of existential matching.  Each time through the loop it would
+>> call match_glob().  match_glob() in turn will handle the named spec.  I tested this version briefly and it seemed to work.  I remember looking at this again later and wondering if I had mis-understood
+>> some of the logic in match_link(), which might mean there are cases where you would need an explicit call to check_named_spec_existential() - I never checked it properly after having that thought.
+

 > * 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
 > * 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


@@ -218,13 +239,28 @@ account all comments above (which doesn't mean it is above reproach :) ).  --[[W
 >   that is not a page name at all, and it could be weird
 >   if such a parameter were accidentially interpreted as a named
 >   pagespec. (But, that seems unlikely to happen.)
 >   that is not a page name at all, and it could be weird
 >   if such a parameter were accidentially interpreted as a named
 >   pagespec. (But, that seems unlikely to happen.)

+
+>> Possibly.  I'm not sure which I prefer between the current solution and that one.  Each have advantages and disadvantages.
+>> It really isn't much code for the match functions to add a call to check_named_spec_existential().
+

 > * 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
 >   myself..
 > * 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
 >   myself..

->  
+
+>> It worked for me. :)
+

 > --[[Joey]] 
 
 > --[[Joey]] 
 

+>>  There is one issue that I've been thinking about that I haven't raised anywhere (or checked myself), and that is how this all interacts with page dependencies.
+>>  Firstly, I'm not sure anymore that the `pagespec_merge` function will continue to work in all cases.  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.  The second type is "rebuild this page when
+>> set of pages referred to by this pagespec changes" - ikiwiki doesn't seem to handle this.  I suspect that named pagespecs would make that second type of dependency more
+>> important.  I'll try to come up with a good example. -- [[Will]]
+
+>>> Hrm, I was going to build an example of this with backlinks, but it looks like that is handled as a special case at the moment (line 458 of render.pm).  I'll see if I can break
+>>> things another way.  Fixing this properly would allow removal of that special case. -- [[Will]]
+

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     diff --git a/IkiWiki.pm b/IkiWiki.pm
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     diff --git a/IkiWiki.pm b/IkiWiki.pm