bug#57955: 29.0.50; Allow session-local ERC modules

[J.P.]

Tags: patch

Hi people,

Since its inception, ERC has aimed to support local modules, that is,
modules local to a connection. (If you need convincing of this, take a
look at `define-erc-module'.) This makes sense for a good many reasons,
chief among them simplified semantics when arranging for buffer-local
variables and hooks. Ancillary benefits include let-binding
`erc-modules' around entry-point invocations and selectively disabling
modules for particular sessions (e.g., after capability negotiation).

Unfortunately, this dream of ERC's authors was never fully realized.
Take a look at `erc-open', where you'll find would-be local vars being
set too early and thus clobbered when `erc-mode' (the major mode) is
activated. Various kludges have come along to circumvent this. For
example, the log module uses `erc-connect-pre-hook' to conduct its
buffer-local business. But it shouldn't have to. ERC can do better.

This patch aims to address this problem by partially changing the
purpose of the function `erc-update-modules' in a backward compatible
way. Instead of activating local modules immediately, it now returns
them in a list to be activated at a time and place of the caller's
choosing. The most opportune place for this, in terms of `erc-open', is
after all the core local variables have been determined, which exposes
them to module setup code. As a bonus, the major mode hook is likewise
deferred to this point.

This patch also reworks the module-to-features map and preferred-name
migration logic, which was incomplete. As far as third-party packages
are concerned, it's only been tested with erc-hl-nicks, thus far, but it
"should" work with others too. (Please let me know if that's a lie.)

Thanks,
J.P.

P.S. BTW, if anyone is friendly with the hl-nicks author, please ask
them to reach out regarding an unrelated custom.el issue; attempts to
contact them via GitHub have so far proven unsuccessful.


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0002-Support-local-ERC-modules-in-erc-mode-buffers.patch
Description: Text Data