img: Support a title attribute, will be passed through to html. Closes: #478718

[git.ikiwiki.info.git] / doc / plugins / write / external.mdwn

diff --git a/doc/plugins/write/external.mdwn b/doc/plugins/write/external.mdwn
index 058b9e58a2da357c925dc1507e3d904120a61ba5..bda34b77188301c67cdf30c7dc85ac5ab492c008 100644 (file)
--- a/doc/plugins/write/external.mdwn
+++ b/doc/plugins/write/external.mdwn
@@ -54,7 +54,7 @@ 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
 call `setstate("page", "id", "key", "value")`.
 
 To access ikiwiki's ARGV array, call `getargv()`. To change its ARGV, call

-`setargv(value)`.
+`setargv(array)`.

 
 ## Notes on function parameters
 
 
 ## Notes on function parameters
 


@@ -79,6 +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.
 
 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
 ## Function injection
 
 Some parts of ikiwiki are extensible by adding functions. For example, the