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.

Here's a patch[[!tag patch]] to achieve this (also in the "defaultmeta" branch of
my github ikiwiki fork):

    diff --git a/IkiWiki/Plugin/meta.pm b/IkiWiki/Plugin/meta.pm
    index b229592..a307db4 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 ($$;@) {
    @@ -324,4 +334,5 @@ sub match_copyright ($$;@) {
            IkiWiki::Plugin::meta::match("copyright", @_);
     }
     
    +
     1
    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 `"` 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]]