Raise File.Error exception on non existing file

[gpopides]

refs #137

[mruoss]

Thanks for this. It does solve the issue at hand. However, File.read() also returns other tuples. So maybe there's other cases to deal with at some point. But this solves already the most common one.

Hmm... you should not have such a hard time with the pipeline. Let me fix that on develop branch so you can rebase.

[gpopides]

Hey, i thought about the other tuples but i was not sure if File.Error is the right exception for all of them. Let me know if you want to address this in this PR

[mruoss]

You can rebase now and pipeline should be fine.
As for your question, I'm undecided on how to deal with this. One possibility is to refactor so that from_file/2 calls from_file!/2, rescues exceptions and turns them into tuples. But afaik that's generally not a very good idea because exceptions should be avoided... Maybe a topic for the elixir forum...

[gpopides]

File.read!/1 returns always File.Error, so i think always raising File.Error from from_file!/2 would be an option.

[mruoss]

What if in render where we know the error comes from File.read we turn it into a {:error, %File.Error{...}} tuple with :reason set accordingly?

Also see File.read!

[gpopides]

from_file also may return a yaml parsing error. Do we want to distinguish handling between File.Error and Yaml.ParsingError ?

[mruoss]

If we turn the {:error, atom()} tuple in render/2 into a {:error, %File.Error{}} tuple, we can leave the code in from_file! as is. It's just gonna raise the File.Error (or Yaml.ParsingError if is returned):

[mruoss]

This is unrelated and should not be necessary now... right?

[mruoss]

Thanks @gpopides. Committed a slight change in 6990b83.