Hook Types: Parameters and Return Values
-----------------------------------------
-Hooks, when executed, are called with one parameter, an array of data
-that is passed to the hook. The first element in the array is the name
-of the hook that is being called. Any other elements in the array are
-dependant on the type of hook that is being called. Most hooks do not
-pass any other data, but be sure to check the hook you are using for
-any useful information it may provide. Generally speaking, in the case
-that any extra data is available here, your plugin should NOT change
-it unless you know what you are doing or it is documented otherwise.
-See below for further discussion of special hook types and the values
+Hooks, when executed, are called with differing parameters and may or may
+not take return values, all depending on the type of hook being called and
+the context in which it is being used. On the source side (where the hook
+call originates), all hooks have at least one parameter, which is the
+name of the hook. After that, things get complicated.
+
+ do_hook
+ -------
+ Most hook calls don't pass any data and don't ask for anything back.
+ These always use the do_hook call. A limited number of do_hook calls do
+ pass some extra parameters, in which case your plugin may modify the
+ given data if you do so by reference. It is not necessary to return
+ anything from your function in such a case; modifying the parameter
+ data by reference is what does the job (although the hook call itself
+ (in the source) must grab the return value for this to work). Note
+ that in this case, the parameter to your hook function will be an array,
+ the first element simply being the hook name, followed by any other
+ parameters that may have been included in the actual hook call in the
+ source. Modify parameters with care!
+
+ do_hook_function
+ ----------------
+ This hook type was intended to be the main hook type used when the
+ source needs to get something back from your plugin. It is somewhat
+ limited in that it will only use the value returned from the LAST
+ plugin registered against the hook. The source for this hook might
+ use the return value for internal purposes, or might expect you to
+ provide text or HTML to be sent to the client browser (you'll have to
+ look at its use in context to understand how you should return values
+ here). The parameters that your hook function gets will be anything
+ you see AFTER the hook name in the actual hook call in the source.
+ These cannot be changed in the same way that the do_hook parameters
+ can be.
+
+ concat_hook_function
+ --------------------
+ This is a newer hook type meant to address the shortcomings of
+ do_hook_function; specifically in that it uses the return values of
+ all plugins registered against the hook. In order to do so, the
+ return value is assumed to be a string, which is just piled on top
+ of whatever it got from the other plugins working on the same hook.
+ Again, you'll have to inspect the source code to see how such data
+ is put to use, but most of the time, it is used to create a string
+ of HTML to be inserted into the output page. The parameters that
+ your hook function will get are the same as for the do_hook_function;
+ they are anything AFTER the hook name in the actual hook call in the
+ source.
+
+ boolean_hook_function
+ ---------------------
+ The newest of the SquirrelMail hooks, this type is used to let all
+ plugins registered against the hook to "vote" for some action. What
+ that action is is entirely dependent on how the hook is used in the
+ source (look for yourself). Plugins make their "vote" by returning
+ TRUE or FALSE. This hook may be configured to "tally votes" in one
+ of three ways. This configuration is done with the third parameter
+ in the hook call in the source:
+ > 0 -- Any one or more TRUEs will override any FALSEs
+ < 0 -- Any one or more FALSEs will override any TRUEs
+ = 0 -- Majority wins. Ties are broken in this case with
+ the last parameter in the hook call in the source.
+ Your hook function will get the second paramter in the hook call in
+ the source as its parameter (this might be an array if multiple values
+ need to be passed).
-Most hooks, when executed, are called using the do_hook() function,
-where no return value is used. There are a limited number of hooks,
-however, that are called using the do_hook_function() and
-concat_hook_function() function calls. Both of these hook types may
-use the value returned by your plugin for its own purposes or to
-display in the resultant HTML output (you need to research the specific
-hook to determine its use). The do_hook_function() type hook will
-only use the return value it retrieves from the LAST plugin in the
-list of plugins registered against such a hook, whereas the
-concat_hook_function() type hook will concatenate the return values
-from all plugins that are registered against the hook and use that
-value (usually as a string of HTML code to output to the client).
+See below for further discussion of special hook types and the values
List of Hooks
Hook Name Found In Called With(#)
--------- -------- --------------
loading_constants functions/constants.php do_hook
+ logout_error functions/display_messages.php do_hook
+ error_box functions/display_messages.php concat_hook
get_pref_override functions/file_prefs.php hook_func
get_pref functions/file_prefs.php hook_func
special_mailbox functions/imap_mailbox.php hook_func
% rename_or_delete_folder functions/imap_mailbox.php hook_func
- msg_envelope functions/mailbox_display.php do_hook
mailbox_index_before functions/mailbox_display.php do_hook
mailbox_form_before functions/mailbox_display.php do_hook
mailbox_index_after functions/mailbox_display.php do_hook
message_body functions/mime.php do_hook
^ attachment $type0/$type1 functions/mime.php do_hook
attachments_bottom functions/mime.php hook_func
+ decode_body functions/mime.php hook_func
generic_header functions/page_header.php do_hook
menuline functions/page_header.php do_hook
internal_link functions/page_header.php hook_func
left_main_after_each_folder src/left_main.php concat_hook
left_main_before src/left_main.php do_hook
left_main_after src/left_main.php do_hook
- create_collapse_link src/left_main.php hook_func
login_cookie src/login.php do_hook
login_top src/login.php do_hook
login_form src/login.php do_hook
After you're done translating, you can create the .mo file very simply
by running the following command (available on most linux systems):
- msgfmt -
0 <plugin name>.mo <plugin name>.po
+ msgfmt -
o <plugin name>.mo <plugin name>.po
In the case of the "demo" plugin:
- msgfmt -0 demo.mo demo.po
+ msgfmt -o demo.mo demo.po
Please be sure that the .po and .mo files both are named exactly the
same as the domain you bound in step 2 above and everything else works
and change your Language setting to see the translations in action!
+
+Documenting the Code (Optional)
+-------------------------------
+
+If you wish, you can use phpdoc (Javadoc-style) comments, when documenting your
+code.
+
+If you follow the standards that are followed between Squirrelmail core &
+plugin developers, the resulted documentation can be included with the rest of
+the Squirrelmail code & API documentation. Specifically, in the page-level
+docblock, declare the package to be 'plugins', and the subpackage to be the
+name of your plugin. For instance:
+
+/**
+ * demo.php
+ *
+ * Copyright (c) 2003 My Name <my-email-address>
+ * Licensed under the GNU GPL. For full terms see the file COPYING.
+ *
+ * @package plugins
+ * @subpackage demo
+ */
+
+The rest is up to you. Try to follow some common sense and document what is
+really needed. Documenting the code properly can be a big help not only to
+yourself, but to those who will take a look at your code, fix the bugs and even
+improve it, in the true open-source spirit that Squirrelmail was built upon.
+
+For more information about phpdocumentor and how to write proper-tagged
+comments, you are directed at:
+
+http://phpdocu.sourceforge.net/
+
+
+
PLUGIN STANDARDS AND REQUIREMENTS
=================================
In order for SquirrelMail to remain fast and lean, we are now asking
that all plugin authors remove all unnecessary functionality from setup.php
-and refactoring it into another file. There are a few ways to accomplish
+and refactor it into another file. There are a few ways to accomplish
this, none of which are difficult. At a minimum, you'll want to have the
squirrelmail_plugin_init_<plugin name>() function in setup.php, and naturally,
you'll need functions that are merely stubs for each hook that you are using.
turned all the way up. You can do this by changing two settings in your
php.ini and restarting your web server:
- display_errors = Off
+ display_errors = On
error_reporting = E_ALL
This way, you'll be sure to see all Notices, Warnings and Errors that your
projects / squirrelmail.git / blobdiff