Draft patch: Supporting buffer-local `erc-hide-*'

[Alcor]

Hi Erc'ers,

I've tried modifying Erc to support buffer-local erc-hide-*
variables. The idea is to support message type filtering per channel
buffer, which is useful for "noisy" channels.

Attached is a patch with an implementation idea, which I have tested out
for a couple of hours. The approach is as follows:

1. Extract out a function `erc-buffer-expand' (perhaps a different name
might be better?) from `erc--route-insertion' that normalizes Erc's
buffer specification values to lists.

2. Add a helper `erc-hide-current-message-in-buffer-p' that evaluates
`erc-hide-current-message-p' in a (with-current-buffer ...) context.

3. Modify `erc-display-message' to use #1 & #2, ensuring only non-hidden
messages as per the predicate from #2 get inserted.

Feedback welcome. I'm still a bit dissatisfied with some aspects of the
patch and am left wondering if there's a way to avoid adding an extra
argument to `erc--route-insertion'. Testing on a number of IRC channels
with (setq-local erc-hide-list '("PART" "JOIN" "QUIT")) while comparing
with the defaults yields good results however, with all specified
messages being correctly filtered out.

Cheers,
-A.

PS: Regarding the terminology - "erc-hide-*" feels slightly
misleading. I'm not familiar with Erc's internals but I have not found a
way to "unhide" messages, so this feature (as it is) is more of
"discard" or "drop" compared to the similarly-named functionality in
Circe, which is reversible.

0001-Support-buffer-local-erc-hide-list-erc-channel-hide-.patch
Description: Text Data