Then you want to use a case. Your variant is inherently unsafe, as there is
no guarantee the "post" variable has been set or not. Elixir was used to
initialize variables to nil but this behaviour has been deprecated since
1.2 or 1.3 as it was very confusing.
*José Valim*
www.plataformatec.com.br
Skype: jv.ptec
Founder and Director of R&D
On Wed, Jul 5, 2017 at 2:16 PM, <m...@lamarciana.com> wrote:
> Hi!
>
> Writing a phoenix application I came across a pattern which I think it
> could be quite common. For example, in a controller:
>
> ```
> with {:ok, post} <- Blog.get_post(id),
> {:ok, :authorized} <- Blog.authorize_post(post),
> {:ok, updated_post} <- Blog.update_post(post, params)
> do
> conn
> |> put_flash("Success!")
> |> render("show.html", conn: conn, post: updated_post)
> else
> {:error, changeset_with_errors} ->
> {:ok, post} <- Blog.get_post(id)
> conn
> |> put_flash("Error!")
> |> render("edit.hml", conn: conn, post: post, changeset:
> changeset_with_errors)
> ```
>
> In the case that the `with` statement matches the first and second match
> but not the third one, then the `else` clause for `{:error,
> changeset_with_errors}` is executed. There, even if `post` variable had
> already been matched in the `with` statement, I need to "match it again" in
> order to use it.
>
> I know I could match it before entering the `with` statement and just
> authorize and update in it, but it is a pity that then the happy path is
> less clear to read.
>
> So, what I'm thinking is that maybe it would be nice to have access, if
> possible, in `else` clauses to the variables that has been matched in the
> `with` part.
>
> What do you think?
>
> Thank you
>
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