Small fixes, denote-rename-file-using-front-matter and signature line only when there is a value

[jeanphilippegg]

In this pull request:

• denote-front-matter-components-present-even-if-empty-value
  defaulting to '(title keywords date identifier). The signature is
  not included so things should keep working as before for users.

• Fixed smalls issues in denote--get-file-components-for-rewrite and
  denote-rewrite-front-matter.

• Moved the backlinks check in denote--rename-file.

• Refactored denote-rename-file-using-front-matter. It was not
  handling all front matter components. Though it was a general issue,
  I think you noticed it when trying to integrate markdown-obsidian.
  It should work now. Check its docstring!

---

markdown-obsidian

I have seen your obsidian branch. I have two small comments:

1- The denote-*-key-regexp should not be empty strings for the
missing components, or else it will match. The default value ensures
that there is no match.

2- #'identity is not a suitable function for the
denote-keywords-value-function and denote-date-value-function. The
reason is that the functions should take a list or a date object as
input and return a string for the front matter. #'identity does not
do that. I know I gave this example in a previous comment. I realized
it was not valid when I tried to give them default values. It may work
anyway because there is no date or keywords in the front matter
template.

So, a correct definition would be:

(add-to-list
 'denote-file-types
 '(markdown-plain
   :extension ".md"
   :front-matter "# %s\n\n"
   :title-key-regexp "^# "
   :title-value-function identity
   :title-value-reverse-function identity
   :link denote-md-link-format
   :link-in-context-regexp denote-md-link-in-context-regexp))

[jeanphilippegg]

Just pushed one last commit.

Ready to be merged!

[jeanphilippegg]

I refactored denote--format-front-matter to remove lines with empty
values (if necessary) from new front matters.

I rebased the branch on top of main.

I think this completes these issues: #474, #366 and #278.

[protesilaos]

Merged, thank you!

I have seen your obsidian branch.

Thank you for the comments! I realised I was using an older version of Denote, which was messing up with my experiment. I just pushed it to the branch to not lose my progress. Will pick it up again as soon as possible.