Re: Changelog message for updating packages

[Jean Louis <bugs@gnu.support>]

* Boruch Baum <boruch_baum@gmx.com> [2020-11-08 13:08]:
> As an emacs user, I would like to know before updating a package what is
> in store for me if I decide to perform an update. As a programmer, I
> would like to inform / warn users of changes or new features when they
> update. This has become a standard feature of linux package managers and
> ought to become a feature of emacs' package.el IMO. For example, in
> debian one can perform 'apt changelog foo' prior to upgrading package
> foo, and a developer can prepare an update message that appears after an
> upgrade (and is also mailed to the admin's mailbox).

You may find it in Emacs Lisp manual under (elisp) Packaging

D.8 Conventional Headers for Emacs Libraries
============================================

‘;;; Change Log:’
     This begins an optional log of changes to the file over time.
     Don’t put too much information in this section—it is better to keep
     the detailed logs in a version control system (as Emacs does) or in
     a separate ‘ChangeLog’ file.  ‘History’ is an alternative to
     ‘Change Log’.

> Participating packages would need to have some standardized changelog
> file and possible message file, and package.el would need one extra
> interactive function and a handler for the possible messages.

Explore those many ready functions. I am using some of them.

    add-change-log-entry
    add-change-log-entry-other-window
    add-log--changelog-buffer-p
    add-log--pseudo-changelog-buffer-name
    add-log-find-changelog-buffer
    change-log-beginning-of-defun
    change-log-end-of-defun
    change-log-fill-forward-paragraph
    change-log-fill-parenthesized-list
    change-log-find-file
    change-log-get-method-definition
    change-log-get-method-definition-1
    change-log-goto-source
    change-log-goto-source-1
    change-log-goto-source-internal
    change-log-indent
    change-log-insert-entries
    change-log-merge
    change-log-mode
    change-log-name
    change-log-next-buffer
    change-log-next-error
    change-log-read-defuns
    change-log-read-entries
    change-log-resolve-conflict
    change-log-search-file-name
    change-log-search-tag-name
    change-log-search-tag-name-1
    change-log-sortable-date-at
    change-log-version-number-search
    diff-add-change-log-entries-other-window
    find-change-log
    log-edit-add-to-changelog
    log-edit-changelog--pattern
    log-edit-changelog-entries
    log-edit-changelog-entry
    log-edit-changelog-insert-entries
    log-edit-changelog-ours-p
    log-edit-changelog-paragraph
    log-edit-changelog-subparagraph
    log-edit-comment-to-change-log
    log-edit-generate-changelog-from-diff
    log-edit-insert-changelog
    log-edit-insert-changelog-entries
    log-edit-insert-filenames-without-changelog
    log-edit-narrow-changelog
    prompt-for-change-log-name
    smart-lisp-at-change-log-tag-p
    vc-cvs-update-changelog
    vc-rcs-update-changelog
    vc-update-change-log