+[[!tag reviewed]]
+[[!template id=gitbranch branch=jon/pagespec_alias author="[[Jon]]"]]
[[!tag patch wishlist]]I quite often find myself repeating a boiler-plate
-pagespec chunk, e.g.
+[[ikiwiki/pagespec]] chunk, e.g.
and !*.png and !*.jpg...
I wrote the following plugin to achieve this:
- commit f3a9dd113338fe5d2b717de1dc69679ff74e2f8d
- Author: Jon Dowland <jmtd@debian.org>
- Date: Tue May 3 17:40:16 2011 +0100
-
- new plugin: alias.pm - pagespec aliases
-
- diff --git a/IkiWiki/Plugin/alias.pm b/IkiWiki/Plugin/alias.pm
- new file mode 100644
- index 0000000..b8d4574
- --- /dev/null
- +++ b/IkiWiki/Plugin/alias.pm
- @@ -0,0 +1,47 @@
- +package IkiWiki::Plugin::alias;
- +
- +use warnings;
- +use strict;
- +use IkiWiki '3.00';
- +
- +sub import {
- + hook(type => "getsetup", id=> "alias", call => \&getsetup);
- + hook(type => "checkconfig", id=> "alias", call => \&checkconfig);
- +}
- +
- +sub getsetup () {
- + return
- + plugin => {
- + description => "allows the definition of pagespec aliases",
- + safe => 1,
- + rebuild => 1,
- + section => "misc",
- + },
- + pagespec_aliases => {
- + type => "string",
- + example => {"image" => "*jpg or *jpeg or *png or *gif or *ico" },
- + description => "a set of mappings from alias name to pagespec",
- + safe => 1,
- + rebuild => 0,
- + },
- +}
- +
- +sub checkconfig () {
- + no strict 'refs';
- + no warnings 'redefine';
- +
- + if ($config{pagespec_aliases}) {
- + foreach my $key (keys %{$config{pagespec_aliases}}) {
- + my $value = ${$config{pagespec_aliases}}{$key};
- + # XXX: validate key?
- + my $subname = "IkiWiki::PageSpec::match_$key";
- + *{ $subname } = sub {
- + my $path = shift;
- + return IkiWiki::pagespec_match($path, $value);
- + }
- + }
- + }
- +}
- +
- +1;
+ <snip old patch; see git branch outlined above>
I need to reflect on this a bit more before I send a pull request. In
particular I imagine the strict/warnings stuff will make you puke. Also, I'm
not sure whether I should name-grab 'alias' since [[todo/alias_directive]] is
an existing wishlist item.
+> I think it would make sense to have "pagespec" in the name somehow.
+
+>> Good idea, how about `pagespecalias`? — [[Jon]]
+
+> No, the strict/warnings does not make me puke. Have you read my perl
+> code? :-P
+>
+> Note that your XXX is right. It would be a security hole to not validate
+> `$key`, as anyone with websetup access could cause it to run arbitrary
+> perl code.
+>
+> Well, except that websetup doesn't currently support configuring hashes
+> like used here. Which is a pity, but has led me to try to avoid using
+> such hashes in the setup file.
+
+> > If I removed the `getsetup` subroutine, it would not be exposed via
+> > website, is that right? I suppose it doesn't hurt to validate key, even if
+> > this risk was not there. Is the use of a hash here a blocker for adoption?
+> > — [[Jon]]
+
+> Have you considered not defining the pagespec aliases in the setup file, but
+> instead as directives on pages in the wiki? Using pagestate could store
+> up the aliases that have been defined. It could however, be hard to get
+> the dependencies right; any page that uses a pagespec containing
+> an alias `foo` would need to somehow depend on the page where the alias
+> was defined. --[[Joey]]
+
+> > I haven't thought the dependency issue through beyond "that might be hard".
+> > Personally, I don't like defining stuff like this in pages, but I appreciate
+> > some do. There could be some complex scenarios where some pages rely on a
+> > pagespec alias defined on others; and could have their meanings changed by
+> > changing the definition. A user might have permission to edit a page with a
+> > definition on it but not on the pages that use it, and similar subtle permission
+> > bugs. I'm also not sure what the failure mode is if someone redefines an alias,
+> > and whether there'd be an unpredictable precedence problem.
+> > How about both methods? — [[Jon]]
+
Here's an example setup chunk:
pagespec_aliases:
-- [[Jon]]
+> Probably needs to be `or internal(*)` --[[Joey]]
+
+> > Ah yes, could be, thanks. — [[Jon]]
+
> another useful pagespec alias for large maps:
basewiki: "sandbox or templates or templates/* or ikiwiki or ikiwiki/* or shortcuts or recentchanges or wikiicons/*"
> -- [[Jon]]
+
+>> Useful indeed! --[[Joey]]
+
+
+>>> I've tweaked my patch in light of your above feedback: The plugin has been
+>>> renamed, and I now validate keys. I've also added documentation and tests
+>>> to the branch. I haven't read rubykat's code properly yet, and don't have
+>>> access at the time of writing (I'm on a beach in Greece ☺), but I expect it
+>>> would be possible to extend what I've got here to support defining the
+>>> aliases in a PageSpec, once the dependency stuff has been reasoned out
+>>> properly.
+>>>
+>>> I'd like to solve the issue of this not being web-configurable by
+>>> implementing support for more nested datatypes in [[plugins/websetup]]. —
+>>> [[Jon]]
+
+>>>> Well, it's a difficult problem. websetup builds a form using
+>>>> CGI::FormBuilder, which makes it easy to build the simple UI we have
+>>>> now, but sorta precludes anything more complicated. And anything with
+>>>> a nested datatype probably needs a customized UI for users to be able
+>>>> to deal with it. I don't think websetupability need be a deal-breaker
+>>>> for this patch. I personally like special pages like Kathryn is doing
+>>>> more than complex setup files. --[[Joey]]
+
+>>>>> I've ran out of time to keep working on this, so I'm just going to
+>>>>> submit it as a 'contrib' plugin and leave things at that for now.
+>>>>> — [[Jon]]
+
+---------------------------
+
+Based on the above, I have written an experimental plugin called "subset".
+It's in my "ikiplugins" repo on github, in the "experimental" branch.
+<https://github.com/rubykat/ikiplugins/blob/experimental/IkiWiki/Plugin/subset.pm>
+
+It takes Joey's suggestion of defining the subsets (aliases) as directives;
+I took the example of the [[plugins/shortcut]] plugin and designated a single special page as the one where the directives are defined,
+though unlike "shortcut" I haven't hardcoded the name of the page; it defaults to "subsets" but it can be re-defined in the config.
+
+I've also added a feature which one might call subset-caching; I had to override `pagespec_match_list` to do it, however.
+An extra parameter added to `pagespec_match_list` called `subset` which
+
+* limits the result to look *only* within the set of pages defined by the subset (uses the "list" option to pagespec_match_list to do this)
+* caches the result of the subset search so that the second time subset "foo" is used, it uses the stored result of the first search for "foo".
+
+This speeds things up if one is using a particular subset more than once, which one probably is if one bothered to define the subset in the first place.
+The speed increase is most dramatic when the site has a large number of pages and the number of pages in the subset is small.
+(this is similar to the "trail" concept I used in my [[plugins/contrib/report]] plugin, but not quite the same)
+
+Note that things like [[plugins/map]] can't make use of "subset" (yet) because they don't pass along all the parameters they're given.
+But [[plugins/contrib/report]] actually works without alteration because it does pass along all the parameters.
+
+Unfortunately I haven't figured out how to do the dependencies - I'd really appreciate help on that.
+
+--[[KathrynAndersen]]
+
+> > Cool! I like the caching idea. I'm not sure about the name. I don't like defining
+> > stuff in pages, but I appreciate this is a matter of taste, and would be happy with
+> > supporting both. — [[Jon]]
+
+>>> I've now gone and completely re-done "subset" so that it is less like an alias, but it a bit clearer and simpler:
+>>> instead of having a separate "match_" function for every alias, I simply have one function, "match_subset"
+>>> which takes the name of the subset. Thus a \[[!subset name="foo"...]] would be called `subset(foo)` rather than `foo()`.
+
+>>> There are a few reasons for this:<br/>
+>>> (a) it's more secure not to be evaluating code on the fly<br/>
+>>> (b) it's simpler<br/>
+>>> (c) (and this was my main reason) it makes it possible to do caching without having to have a separate "subset" argument.
+>>> I've done a bit of a hack for this: basically, the PageSpec is checked to see if the very start of the PageSpec is `subset(foo) and` or if the whole pagespec is just `subset(foo)` and if either of those is true, then it does the subset caching stuff.
+>>> The reason I check for "and" is that if it is "subset(foo) or something" then it would be an error to use the subset cache in that case.
+>>> The reason I just check the start of the PageSpec is because I don't want to have to do complex parsing of the PageSpec.
+
+>>> As for defining subsets in the config rather than on pages, I perfectly understand that desire, and I could probably add that in.
+
+>>> As for the name "subset"... well, it's even less like an alias now, and "alias" is already a reserved name. What other names would you suggest?
+
+>>>--[[KathrynAndersen]]
+
+>>>> Regarding my comments: I wasn't clear what you are/were intending to
+>>>> achieve with your modifications. I've aimed for a self-contained plugin
+>>>> which could be merged with ikiwiki proper. I think I initially took your
+>>>> developments as being an evolution of that with the same goal, which is
+>>>> why I commented on the (change of) name. However, I guess your work is
+>>>> more of a fork than a continuation, in which case you can call it
+>>>> whatever you like ☺ I like some of the enhancements you've made, but
+>>>> having the aliases/subsets/"things" work in any pagespec (inside map, or
+>>>> inline) is a deal-breaker for me. — [[Jon]]
+
+>>>>> I'm a bit confused by your statement "having the aliases/subsets/"things" work in any pagespec (inside map, or inline) is a deal-breaker for me".
+>>>>> Do you mean that you want them to work in any pagespec, or that you *don't* want them to work in any pagespec? -- [[KathrynAndersen]]
+
+>>>>>> I mean I would want them to work in any pagespec. — [[Jon]]
+
+----
+
+Hi, it's been 7 years since I last looked at this, and I'm surprised to find
+that I'd got it up to a merge-request state; I've dusted it off and done some
+clean up and testing, but it's working (albeit not via websetup). I've revamped
+the docs and rebased the branch. Can someone please consider merging ([[joey]]
+or [[smcv]]?) or otherwise feed back on this? Thanks! — [[Jon]] (2018-09-25)
+
+> To hide it from `websetup`, the `example` needs to be a hash reference
+> like `example => { images => "*.png or *.jpg or *.gif" }`, I think?
+> (Please try it on a websetup-enabled wiki, possibly by copying
+> `t/manual/git_revert` to `t/manual/websetup` and adapting it as required.)
+>
+> For a less magical variant, you could consider using `alias(images)`
+> instead of `images()` for the pagespec syntax that is enabled by the
+> example above. I'm not sure which way is better.
+>
+> If `safe_key` fails, you probably want to log a warning, or even fail
+> `checkconfig` with a fatal `error`?
+>
+> If `checkconfig` detects that the given pagespec function already
+> exists, for example `title` after loading the meta plugin, you probably
+> want to log a warning or fail? It seems you can detect this with
+> `defined ref *$subname{CODE}`.
+>
+> If you define a loop of mutually recursive aliases (or even an alias
+> that refers to itself), I think you'll get infinite recursion.
+> You can probably bypass that with a construct like:
+>
+> my $entered;
+> *{ $subname } = sub {
+> return IkiWiki::ErrorReason->new("Alias $key is defined recursively") if $entered;
+> $entered = 1;
+> my $result = IkiWiki::pagespec_match($path, $value);
+> $entered = 0;
+> return $result;
+> }
+>
+> (but don't take my word for it, a regression test would tell you whether
+> this works.)
+>
+> --[[smcv]]