X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/840585338ee9c6ff4e91b8788c3f7d91b4362a42..6f852e88e30775cb2238f301bb7ca1c4a83d59f4:/doc/plugins/write/external.mdwn

diff --git a/doc/plugins/write/external.mdwn b/doc/plugins/write/external.mdwn
index fd343bda6..bda34b771 100644
--- a/doc/plugins/write/external.mdwn
+++ b/doc/plugins/write/external.mdwn
@@ -53,6 +53,9 @@ it, external plugins can use the `getstate` and `setstate` RPCs. To access
 stored state, call `getstate("page", "id", "key")`, and to store state,
 call `setstate("page", "id", "key", "value")`.
 
+To access ikiwiki's ARGV array, call `getargv()`. To change its ARGV, call
+`setargv(array)`.
+
 ## Notes on function parameters
 
 The [[plugin_interface_documentation|write]] talks about functions that take
@@ -76,6 +79,19 @@ Other languages might not find it so easy. If not, it might be a good idea
 to convert these named parameters into something more natural for the
 language as part of their XML RPC interface.
 
+## undef
+
+XML RPC has a limitation that it does not have a way to pass
+undef/NULL/None. There is an extension to the protocol that supports this,
+but it is not yet available in the [[cpan XML::RPC]] library used by
+ikiwiki.
+
+Until the extension is available, ikiwiki allows undef to be communicated
+over XML RPC by passing a sentinal value, a hash with a single key "null"
+with a value of an empty string. External plugins that need to communicate
+null values to or from ikiwiki will have to translate between undef and
+the sentinal.
+
 ## Function injection
 
 Some parts of ikiwiki are extensible by adding functions. For example, the
@@ -99,9 +115,6 @@ with functions that take or return such references. That means you can't
 FormBuilder perl objects), or use it to call `template()` (which returns a
 perl HTML::Template object).
 
-Also. the `getopt` hook doesn't work, as ARGV is not available to the external
-plugin.
-
 ## Performance issues
 
 Since each external plugin is a separate process, when ikiwiki is