[PATCH] Document custom org agenda functions

[thecashewtrader]

---
 org-tutorials/org-custom-agenda-commands.org | 40 +++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/org-tutorials/org-custom-agenda-commands.org 
b/org-tutorials/org-custom-agenda-commands.org
index e54bcef3..5b55ebb5 100644
--- a/org-tutorials/org-custom-agenda-commands.org
+++ b/org-tutorials/org-custom-agenda-commands.org
@@ -64,7 +64,7 @@ command is a list consisting of the following:
                     (optional).
 - 3) Type of search :: The desired agenda display/search. The options
      include agenda, todo, search, tags, alltodo, tags-todo,
-     todo-tree, tags-tree, occur-tree, or a user-defined function.
+     todo-tree, tags-tree, occur-tree, or a [[*User Defined 
Functions][user-defined function]].
 - 4) Search term :: Depending on the type of search, this will be a
                     TODO keyword, a tag (or property), a word, or a
                     regular expression.
@@ -372,6 +372,44 @@ deadlines and nothing else.
 Tip: if you want to exclude all agenda entry types, just set
 =org-agenda-entry-types= to nil.
 
+* User Defined Functions
+** Function Signature
+User defined functions should:
+
+- Optionally accept one parameter i.e. the =match= variable. The Org agenda 
dispatch function will call the user-defined function with one parameter 
representing the =match= component from the agenda definition. In other words, 
~(udf/test "Hello")~ in =org-agenda-custom-commands= will result in a function 
call of ~udf/test~ with an argument of ="Hello"=.
+
+- Prepare a buffer to write the agenda information to using 
~org-agenda-prepare~.
+
+- Handle setting a unique buffer name for the cases where =org-agenda-sticky= 
has a value of =t=.
+
+- Honor the setting of =org-agenda-overriding-header= and insert that text 
into the agenda buffer. This can be done using the macro 
~org-agenda--insert-overriding-header~.
+
+- Insert into the buffer the desired contents, accounting for also setting 
text properties.
+
+- Call ~org-agenda-finalize~ and ~(setq buffer-read-only t)~
+
+** Example
+This is a simple function to insert notes into the Agenda.
+
+*NOTE: This example is not fully complete as it doesn't respect 
=org-agenda-sticky=.*
+
+#+begin_src emacs-lisp
+
+(defun udf/org-agenda-notes (&optional arg)
+  (org-agenda-prepare "Notes")
+  (org-agenda--insert-overriding-header "Notes")
+  (let ((org-agenda-notes
+         (list "Note 1"
+               "Note 2"
+               "Note 3")))
+    (dolist (note org-agenda-notes)
+          (insert (format "- %s\n" note))))
+  (org-agenda-finalize)
+  (setq buffer-read-only t))
+
+#+end_src
+
+
 * Other configuration ideas
 
 This section is for additional ideas for configuring
-- 
2.35.1