[MM3-users] Re: (Custom) Plugins: Proper file path(s) for adding a handler?

24 Oct 2023

      On 10/23/23 22:57, Abhilash Raj wrote:
...
On 10/23/23 20:37, Thomas Ward via Mailman-users wrote:
...
I want to add a custom handler that implements customized thread IDs
in the system.  I already have the DB logic worked out, but the
documentation for plugins is NOT clear on how to define a handler in
a plugin, nor does the example plugin in the documentation on Gitlab
have any custom handlers.
I'm looking to add a custom handler so that the private pipeline for
threaded-subject-list can use thread-subject (the custom handler)
instead of subject-prefix (builtin).
https://gitlab.com/mailman/mailman/-/tree/master/src/mailman/plugins/testing...
https://docs.mailman3.org/projects/mailman/en/latest/src/mailman/plugins/doc...
These are two places you can find docs for an example plugin that
ships with Mailman's code. Adding a new "component", like a Handler,
works very similar to the "rules" in the example shown above.
Yeah these're helpful, but the problem I was running into was file
naming schema - I was not aware it's always
PLUGIN/COMPONENT/COMPONENT.py in the naming, which it was not entirely
clear about.  It makes sense now that I look back, but it never hurts to
get clarification.
You will probably need a directory tree like:
example/
    __init__.py
    hooks.py
    handlers/
        __init__.py
        handlers.py

Installing the handler is same as per shown in docs using below (do
note that the above example is the name of the package that is
importable):
<snip>
Finally, you can verify that your handler was loaded properly using
something along the lines of:
$ mailman shell
Welcome to the GNU Mailman shell
Use commit() to commit changes.
Use abort() to discard changes since the last commit.
Exit with ctrl+D does an implicit commit() but exit() does not.

>>> for each in config.handlers:
...     print(each)
...
&lt;snip>

The only other thing that was missing is how to set up the proper code
for a Handler implementation/class, which I used an existing mailman3
core plugin as an example to just run with for testing purposes.
There are notes in the example plugin on Gitlab and the documentation
that "other components will be added as examples eventually" but that
was well over a year ago, so we'll see how that ages.
Thanks for the assist!
Thomas