2

I asked How can I script emacs to install packages from list? and got this answer.

(setq package-selected-packages
      '(async
        epl
        evil
        goto-chg
        helm
        helm-ag
        helm-core
        helm-descbinds
        helm-projectile
        pkg-info
        popup
        projectile
        undo-tree))
(package-install-selected-packages)

When I inspect the value of the variable package-activated-list in my installation the output is (evil goto-chg undo-tree goto-chg helm-ag helm helm-core async popup async helm-descbinds helm helm-core async popup async helm-projectile projectile pkg-info epl helm helm-core async popup async popup projectile pkg-info epl undo-tree)

How could I insert the literal output of package-activated-list into the buffer, after the quote. ie generate the script 

(setq package-selected-packages
      '
      ;;<<list of  `package-activated-list` goes here >>
      )
(package-install-selected-packages)

It would be better with duplicates removed and sorted, but those are secondary issues.

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13
  • I don't understand the question. You want to generate (setq package-selected-packages '(async … undo-tree)), right? Do you want to generate just this snippet or a function? If a function, what arguments should it take? And most importantly, what input does the generator take?
    – Gilles 'SO- stop being evil'
    Commented Jul 16, 2017 at 8:48
  • You seem to be dead-set on using quote. Is there a reason why just not quoting the variable won't work for you?
    – wasamasa
    Commented Jul 16, 2017 at 9:01
  • @Gilles I am now learning both emacs and elisp so generating it as function and generating it as snippet are both of interest to me, but my original aim is to generate it as a function, meaning it would involve a call to a function which takes the text template of setq(... with a placeholder for whatever variable is involved, which is package-activated-list and a function to deduplicate and sort its output.
    – vfclists
    Commented Jul 16, 2017 at 10:31
  • @wasamasa As an emacs and elisp newbie both methods and when and where they are appropriate are of interest to me.
    – vfclists
    Commented Jul 16, 2017 at 10:33
  • @wasamasa (setq package-selected-packages package-activated-list) won't work for duplicating package-activated-list from one instance of emacs to the init file for setting up emacs on a different machine (as explained in the linked-to question).
    – Peder Klingenberg
    Commented Jul 16, 2017 at 19:26

3 Answers 3

Reset to default
4

If you're writing a script interactively, and want to insert the current value of package-activated-list into that script, you can do that with C-0 M-: package-activated-list RET. Alternatively, if you have the text package-activated-list in your buffer, you can put the point just after it and press C-0 C-x C-e to have the contents of the variable inserted at point. In that case, the original variable name remains, so you may want to remove that afterwards.

If you want transform the value of the variable, you can use any Lisp expression at the M-: prompt, e.g.

M-0 M-: (sort package-activated-list #'string<) RET
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2
  • Second issue: sort takes two arguments. Using (sort package-activated-list #'string<) works.
    – Omar
    Commented Jul 30, 2017 at 18:13
  • True, thanks. Fixed, though I didn't introduce the error. @Gilles - if you're going to add information to other people's answers, at least do it right, please.
    – Peder Klingenberg
    Commented Jul 31, 2017 at 8:02
2

I don't see the big practical use in this, but you could make a function returning the setq form:

(defun generate-setq-form-function (variable value)
  `(setq ,variable 
         ',(sort (delete-dups (copy-tree value))
                 #'(lambda (x y)
                     (string< (symbol-name x) (symbol-name y))))))

This would be called like so: 

(generate-setq-form-function 'package-selected-packages package-activated-list)

If the quote bothers you, you could even wrap it in a macro:

(defmacro generate-setq-form-macro (variable value)
  `(generate-setq-form-function ',variable ,value))

To be called like so:

(generate-setq-form-macro package-selected-packages package-activated-list)

The trouble is that you would still need to evaluate this on the computer with the correct package-activated-list and insert the result in a file if you want it to replicate the list on another computer. So you need to use C-0 M-: and evaluate the call, like in my other answer.

Alternatively, you could mess around with (interactive) declarations and prompts, but this already seems like overkill to me.

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5
  • When I try to enter C-0 M-: the character 0 is inserted into the buffer, ie the scratch buffer. Could there be some fault in my keyboard setup, or is the key not configured by define-key or one of the other keyboard settings?
    – vfclists
    Commented Jul 18, 2017 at 0:33
  • C-0 is supposed to give you a zero prefix argument to a command. It's just a shortcut for C-u 0, so you can try that instead. Numeric prefix arguments are common enough that they have lots of alternative standard bindings. ESC 0 is another one.
    – Peder Klingenberg
    Commented Jul 18, 2017 at 16:20
  • @vfclists Further to Peder's comment, note that M-0 is the same as C-0, but there is no need for a zero prefix argument - any non-negative one will do, so you can also try C-u M-:. See the Emacs Manual node on Numeric Arguments for more information.
    – Basil
    Commented Jul 28, 2017 at 5:39
  • @Basil The difference between a C-0 and C-u is that with a non-zero argument to either M-: or C-x C-e, the inserted value is possibly truncated, subject to eval-expression-print-length and eval-expression-print-level. So in this case there is in fact a need for the zero argument.
    – Peder Klingenberg
    Commented Jul 28, 2017 at 20:20
  • @PederKlingenberg Right you are; I misread the docstring. Sorry about the confusion.
    – Basil
    Commented Jul 28, 2017 at 23:29
2

You can use M-: (insert (format "%s" package-activated-list)).

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