How to control the number of characters for the SHA1 displayed in Magit's log view?

Question

I've noticed some repositories use 7 characters, others 11 when displaying a SHA1.

It looks as if magit uses the output of git log --pretty=oneline --abbrev-commit however I can't see how to configure this to behave differently.

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Incomplete Solutions

Call with arguments

If I call (magit-log-current nil (list "--abbrev=12")) then the log shows at least 12 characters. However refreshing the log view looses the setting.

Set the initial arguments

This also works before refreshing resets the value and looses the SHA1 length I had set.

(put 'magit-log-mode 'magit-log-current-arguments
     (cons "--abbrev=12" (get 'magit-log-mode 'magit-log-default-arguments)))
(call-interactively 'magit-log-current)

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Is there a way to control how many characters I used to display the SHA1 hash in Magit's log view?

Answer 1

Note that using advice isn't ideal, however I couldn't find a way to do this that didn't involve changing my personal git configuration.

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This can be done by adding advice to magit-log-arguments.

(defvar my-magit-log-sha1-size 16)
(defun my-magit-log-arguments-extra (fn-orig &optional mode)
  (pcase-let ((`(,args ,files) (funcall fn-orig mode)))
    (list (append args (list (format "--abbrev=%d" my-magit-log-sha1-size))) files)))

(advice-add 'magit-log-arguments :around #'my-magit-log-arguments-extra)

Answer 2

In a shell, do

git config --global core.abbrev 12

or use --local to set it per project.

You'll have to recreate the log buffer to enable the change.