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Diffstat (limited to 'doc/plugins/write.mdwn')
| -rw-r--r-- | doc/plugins/write.mdwn | 53 |
1 files changed, 23 insertions, 30 deletions
diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn index 1010e76e4..de2b47015 100644 --- a/doc/plugins/write.mdwn +++ b/doc/plugins/write.mdwn @@ -588,36 +588,6 @@ describes the plugin as a whole. For example: This hook is used to inject C code (which it returns) into the `main` function of the ikiwiki wrapper when it is being generated. -### sort - - hook(type => "sort", id => "foo", call => \&sort_by_foo); - -This hook adds an additional [[ikiwiki/pagespec/sorting]] order or overrides -an existing one. - -The callback is given two page names followed by the parameter as arguments, and -returns negative, zero or positive if the first page should come before, -close to (i.e. undefined order), or after the second page. - -For instance, the built-in `title` sort order could be reimplemented as - - sub sort_by_title { - pagetitle(basename($_[0])) cmp pagetitle(basename($_[1])); - } - -and to sort by an arbitrary `meta` value, you could use: - - # usage: sort="meta(description)" - sub sort_by_meta { - my $param = $_[2]; - error "sort=meta requires a parameter" unless defined $param; - my $left = $pagestate{$_[0]}{meta}{$param}; - $left = "" unless defined $left; - my $right = $pagestate{$_[1]}{meta}{$param}; - $right = "" unless defined $right; - return $left cmp $right; - } - ## Exported variables Several variables are exported to your plugin when you `use IkiWiki;` @@ -1140,6 +1110,29 @@ For example, "backlink(foo)" is influenced by the contents of page foo; they match; "created_before(foo)" is influenced by the metadata of foo; while "glob(*)" is not influenced by the contents of any page. +### Sorting plugins + +Similarly, it's possible to write plugins that add new functions as +[[ikiwiki/pagespec/sorting]] methods. To achieve this, add a function to +the IkiWiki::PageSpec package named `cmp_foo`, which will be used when sorting +by `foo` or `foo(...)` is requested. + +The function will be passed three or more parameters. The first two are +page names, and the third is `undef` if invoked as `foo`, or the parameter +`"bar"` if invoked as `foo(bar)`. It may also be passed additional, named +parameters. + +It should return the same thing as Perl's `cmp` and `<=>` operators: negative +if the first argument is less than the second, positive if the first argument +is greater, or zero if they are considered equal. It may also raise an +error using `error`, for instance if it needs a parameter but one isn't +provided. + +You can also define a function called `check_cmp_foo` in the same package. +If you do, it will be called while preparing to sort by `foo` or `foo(bar)`, +with argument `undef` or `"bar"` respectively; it may raise an error using +`error`, if sorting like that isn't going to work. + ### Setup plugins The ikiwiki setup file is loaded using a pluggable mechanism. If you look |