Re: Suggestion: convert dispatchers to use transient

[Samuel Wales]

jus want to state the obvious here in case it is useful [but everybody
probbly lready knows] --- not everybody uses packages or maybe trusts
them has internet etc.

On 2/5/22, João Pedro de Amorim Paula <jpedrodeamorim@gmail.com> wrote:
> On 04 February 2022 08:30, Tim Cross <theophilusx@gmail.com> wrote:
>
>> I'm assuming it is, but I have to admit I'm still not 100% clear on
>> how Emacs handles the situation where you use a library that is both
>> built-in and available in ELPA. Does Emacs use the latest version
>> available or does it use the built-in version until you explicitly
>> select the ELPA versions?
>
> Welp, I happened to ponder the same question after trying to implement a
> function to install packages that are not installed already (I'm not
> using any helper configuration such as use-package, which would already
> handle this). From what I gathered empirically, it appears that if
> something is built-in, Emacs' package.el won't try to install -- it
> checks with package-installed-p on any call to package-install, which
> checks if the package is built-in with package-built-in-p as a fallback
> on cond --, but you can force installation from the archives by passing
> a package description object (defined as package-desc on package.el)
> instead of a symbol
>
>     (let ((pkg-desc (assq 'org package-archive-contents)))
>       (package-install pkg-desc))
>
> and Emacs seems to be loading the newest version when it is a dependency
> of something else. Though I'm not really sure, as most of the packages I
> have from ELPA have the same version as the ones built-in on Emacs
> 28.0.91. I'll try and install Emacs 27 to check this out.
>
> In the mean time, I guess this would be a good opportunity to share a
> couple of functions I have with the purpose of installing packages.
>
>     (defun pkg-description (package)
>       "Return the description for PACKAGE.
>     If PACKAGE is installed, the will be present on `package-alist',
>     otherwise look for it in `package-archive-contents'."
>       (or (cadr (assoc package package-alist))
>           (cadr (assoc package package-archive-contents))))
>
>     (defun pkg-ensure-archive (package)
>       "Install PACKAGE from the archives, if not already installed."
>       (when-let ((pkg-desc (pkg-description package)))
>         (unless (package-installed-p pkg-desc)
>           (package-install-from-archive pkg-desc))))
>
>     (defun require-package (package &optional force)
>       "Ensure that PACKAGE is installed.
>     If FORCE is non-nil, force installation regardless if PACKAGE is
>     built-in or not.
>
>     First, use `package-installed-p' to check if PACKAGE was
>     installed via the Emacs package manager, otherwise, try to
>     `require' PACKAGE; this ensures that we don't require PACKAGE if
>     it was installed using the package manager. If both of those
>     fail, run `package-refresh-contents' and install PACKAGE."
>       (unless (and (not force)
>                    (or (package-installed-p package)
>                        (require package nil 'no-error)))
>         (unless (assoc package package-archive-contents)
>           (package-refresh-contents))
>         (if force
>             (pkg-ensure-archive package)
>           (package-install package))))
>
> On the last one, the main function that I use, if FORCE is non-nil it
> will download and install the package from the archives even if it is
> built-in.
>
> Best regards,
>
> --
> João Pedro de Amorim Paula
> IT undergraduate at Universidade Federal do Rio Grande do Norte (UFRN)
>


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