Which of these code styles do you find preferable?

First option using mut with constructor in the beginning:

  let mut post_form = PostInsertForm::new(
    data.name.trim().to_string(),
    local_user_view.person.id,
    data.community_id,
  );
  post_form.url = url.map(Into::into);
  post_form.body = body;
  post_form.alt_text = data.alt_text.clone();
  post_form.nsfw = data.nsfw;
  post_form.language_id = language_id;

Second option without mut and constructor at the end:

  let post_form = PostInsertForm {
    url: url.map(Into::into),
    body,
    alt_text: data.alt_text.clone(),
    nsfw: data.nsfw,
    language_id,
    ..PostInsertForm::new(
      data.name.trim().to_string(),
      local_user_view.person.id,
      data.community_id,
    )
  };

You can see the full PR here: https://github.com/LemmyNet/lemmy/pull/5037/files

  • al4s
    13·
    2 months ago

    If you’re ever forced to do something the second way, you can also wrap it in braces, that way you end up with an immutable value again:

    let app = {
  let mut app = ...
  ...
  app
};
      • al4s
        6·
        2 months ago

        Yeah if you have the second option, use it, but if the struct has private fields it won’t work.

          • al4s
            2·
            2 months ago

            You can have setters that set private fields, there are also sometimes structs with mixed private and public fields

      • al4s
        2·
        2 months ago

        A scope groups the initialization visually together, while adding the let app = app; feels like it just adds clutter - I’d probably just leave it mut in that case.