summaryrefslogtreecommitdiff
path: root/doc/todo/allow_site-wide_meta_definitions.mdwn
blob: 01cf12c1a26932402aaf17fcfb64c0ba3311fd86 (plain)

[[!tag plugins/meta patch]] [[!template id=gitbranch branch=jon/defaultmeta author="[[Jon]]"]]

I'd like to define [[plugins/meta]] values to apply across all pages site-wide unless the pages define their own: default values for meta definitions essentially.

<snip old patch, see below for latest>

-- [[Jon]]

This doesn't support multiple-argument meta directives like link=x rel=y, or meta directives with special side-effects like updated.

The first could be solved (if you care) by a syntax like this:

meta_defaults => [
    { copyright => "© me" },
    { link => "about:blank", rel => "silly", },
]

The second could perhaps be solved by invoking meta::preprocess from within scan (which might be a simplification anyway), although this is complicated by the fact that some (but not all!) meta headers are idempotent.

--[[smcv]]

Thanks for your comment. I've revised the patch to use the config syntax you suggest. I need to perform some more testing to make sure I've addressed the issues you highlight.

I had to patch part of IkiWiki core, the merge routine in Setup, because the use of possibly_foolish_untaint was causing the hashrefs at the deep end of the data structure to be converted into strings. The specific change I've made may not be acceptable, though -- I'd appreciate someone providing some feedback on that hunk!

Well, re that hunk, taint checking is currently disabled, but if the perl bug that disallows it is fixed and it is turned back on, the hash values will remain tainted, which will probably lead to problems.

I'm also leery of using such a complex data structure in config. The websetup plugin would be hard pressed to provide a UI for such a data structure. (It lacks even UI for a single hash ref yet, let alone a list.)

Also, it seems sorta wrong to have two so very different syntaxes to represent the same meta data. A user without a lot of experience will be hard pressed to map from a directive to this in the setup file.

All of which leads me to think the setup file could just contain a text that could hold meta directives. Which generalizes really to a text that contains any directives, and is, perhaps appended to the top of every page. Which nearly generalizes to the sidebar plugin, or perhaps something more general than that...

However, excessive generalization is the root of all evil, so I'm not necessarily saying that's a good idea. Indeed, my memory concerns below invalidate this idea pretty well. --[[Joey]]

diff --git a/IkiWiki/Plugin/meta.pm b/IkiWiki/Plugin/meta.pm
index 6fe9cda..2f8c098 100644
--- a/IkiWiki/Plugin/meta.pm
+++ b/IkiWiki/Plugin/meta.pm
@@ -13,6 +13,8 @@ sub import {
 	hook(type => "needsbuild", id => "meta", call => \&needsbuild);
 	hook(type => "preprocess", id => "meta", call => \&preprocess, scan => 1);
 	hook(type => "pagetemplate", id => "meta", call => \&pagetemplate);
+	hook(type => "scan", id => "meta", call => \&scan)
+		if $config{"meta_defaults"};
 }
 
 sub getsetup () {
@@ -305,6 +307,15 @@ sub match {
 	}
 }
 
+sub scan() {
+	my %params = @_;
+	my $page = $params{page};
+	foreach my $default (@{$config{"meta_defaults"}}) {
+		preprocess(%$default, page => $page,
+			destpage => $page, preview => 0);
+	}
+}
+
 package IkiWiki::PageSpec;
 
 sub match_title ($$;@) {
diff --git a/IkiWiki/Setup.pm b/IkiWiki/Setup.pm
index 8a25ecc..e4d50c9 100644
--- a/IkiWiki/Setup.pm
+++ b/IkiWiki/Setup.pm
@@ -51,7 +51,13 @@ sub merge ($) {
 					$config{$c}=$setup{$c};
 				}
 				else {
-					$config{$c}=[map { IkiWiki::possibly_foolish_untaint($_) } @{$setup{$c}}]
+					$config{$c}=[map {
+						if(ref $_ eq 'HASH') {
+							$_
+						} else {
+							IkiWiki::possibly_foolish_untaint($_)
+						}
+					} @{$setup{$c}}];
 				}
 			}
 			elsif (ref $setup{$c} eq 'HASH') {
diff --git a/doc/ikiwiki/directive/meta.mdwn b/doc/ikiwiki/directive/meta.mdwn
index 000f461..8d34ee4 100644
--- a/doc/ikiwiki/directive/meta.mdwn
+++ b/doc/ikiwiki/directive/meta.mdwn
@@ -12,6 +12,16 @@ also specifies some additional sub-parameters.
 The field values are treated as HTML entity-escaped text, so you can include
 a quote in the text by writing `&quot;` and so on.
 
+You can also define site-wide defaults for meta values by including them
+in your setup file. The key used is `meta_defaults` and the value is a list
+of hashes, one per meta directive. e.g.:
+
+	meta_defaults = [
+		{ copyright => "Copyright 2007 by Joey Hess" },
+		{ license   => "GPL v2+" },
+		{ link => "somepage", rel => "site entrypoint", },
+	],
+
 Supported fields:
 
 * title

-- [[Jon]]

Ok, I've had a bit of a think about this. There are currently 15 supported meta fields. Of these: title, licence, copyright, author, authorurl, and robots might make sense to define globally and override on a per-page basis.

Less so, description (due to its impact on map); openid (why would someone want more than one URI to act as an openid endpoint to the same place?); updated. I can almost see why someone might want to set a global updated value. Almost.

Not useful are permalink, date, stylesheet (you already have a global stylesheet), link, redir, and guid.

In other words, the limitations of my first patch that [[smcv]] outlined are only relevant to defined fields that you wouldn't want to specify a global default for anyway.

I generally agree with this. It is possible that meta would have a new field added, that takes parameters and make sense to use globally. --[[Joey]]

Due to this, and the added complexity of the second patch (having to adjust IkiWiki/Setup.pm), I think the first patch makes more sense. I've thus reverted to it here.

Is this merge-worthy?

diff --git a/IkiWiki/Plugin/meta.pm b/IkiWiki/Plugin/meta.pm
index b229592..3132257 100644
--- a/IkiWiki/Plugin/meta.pm
+++ b/IkiWiki/Plugin/meta.pm
@@ -13,6 +13,7 @@ sub import {
 	hook(type => "needsbuild", id => "meta", call => \&needsbuild);
 	hook(type => "preprocess", id => "meta", call => \&preprocess, scan => 1);
 	hook(type => "pagetemplate", id => "meta", call => \&pagetemplate);
+	hook(type => "scan", id => "meta", call => \&scan);
 }
 
 sub getsetup () {
@@ -302,6 +303,15 @@ sub match {
 	}
 }
 
+sub scan() {
+	my %params = @_;
+	my $page = $params{page};
+    foreach my $type (map { s/^meta_//; $_ } grep /^meta_/, keys %config) {
+		$pagestate{$page}{meta}{$type} = $config{"meta_$type"}
+			unless defined $pagestate{$page}{meta}{$type};
+	}
+}
+
 package IkiWiki::PageSpec;
 
 sub match_title ($$;@) {
diff --git a/doc/ikiwiki/directive/meta.mdwn b/doc/ikiwiki/directive/meta.mdwn
index 000f461..200c4b2 100644
--- a/doc/ikiwiki/directive/meta.mdwn
+++ b/doc/ikiwiki/directive/meta.mdwn
@@ -12,6 +12,12 @@ also specifies some additional sub-parameters.
 The field values are treated as HTML entity-escaped text, so you can include
 a quote in the text by writing `&quot;` and so on.
 
+You can also define site-wide defaults for meta values by including them
+in your setup file, e.g.
+
+	meta_copyright => "Copyright 2007 by Joey Hess",
+	meta_license   => "GPL v2+",
+
 Supported fields:
 
 * title

-- [[Jon]]

Merry Christmas/festive season/happy new year folks. I've been away from ikiwiki for the break, and now I've returned to watching recentchanges. Hopefully I'll be back in the mix soon, too. In the meantime, Joey, have you had a chance to look at this yet? -- [[Jon]]

Ping :) Hi. [[Joey]], would you consider this patch for the next ikiwiki release? -- [[Jon]]

For this to work with websetup and --dumpsetup, it needs to define the meta_* settings in the getsetup function.

I also have some concerns about both these patches, since both throw a lot of redundant data at meta, which then stores it in a very redundant way. Specifically, meta populates a per-page %metaheaders hash as well as storing per-page metadata in %pagestate. So, if you have a wiki with 10 thousand pages, and you add a 1k site-wide license text, that will bloat the memory usage of ikiwiki by in excess of 2 megabytes. It will also cause ikiwiki to write a similar amount more data to its state file which has to be loaded back in each run.

Seems that this could be managed much more efficiently by having meta special-case the site-wide settings, not store them in these per-page data structures, and just make them be used if no per-page metadata of the given type is present. --[[Joey]]