Hi!
with is the right tool when you want this kind of error handling in these
function pipelines :)
Cheers,
Louis
On 15 Aug 2016 12:12, "Alvise Susmel" <alv...@poeticoding.com> wrote:
> Hi,
>
> I've started thinking about this, as maybe many of you, when I needed to
> stop the pipe when an error is returned. I've seen that there are different
> conversation about this, but I haven't clear what is the *elixir way* to
> handle errors using pipes.
>
> I see two ways for achieving the same result.* The first* is to use the
> *pipe* *|>* and for each function catch the error and propagate it down.
> The error has to be always returned with the same pattern, like {:error,
> reason}
>
> connect
> |> receive_image
> |> resize
> |> rotate
> |> save
>
>
> If *receive_image* returns an error, *resize* needs to handle it
>
> def resize({:error, _}=error), do:error
>
> and to propagate it down through the pipe. So *rotate* needs to do the
> same, etc..
>
> *The* *second* way I see is using the *with*, which to me seems to be
> more generic (and less clean)
>
> with {:ok, pid} <- connect,
> {:ok, image} <- receive_image(pid),
> {:ok, resized_image} <- resize(image),
> {:ok, rotated_image} <- rotate(resized_image),
> :ok <- save(rotated_image)
> do: IO.puts "saved"
>
>
> Now, the cool thing about *with* is that when one of the assignments
> fails, it exits returning the value that failed the pattern match.
>
> So, to you, what is the elixir way on handling the return errors on pipes
> ? Could *"with" *be seen as a new (and more generic) way of piping with
> error handling ?
>
> Thanks
>
> Alvise
>
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