Meeseeks.Error
Prior to v0.9.0, errors in Meeseeks were all over the place- sometimes they returned {:error, string} or :error, sometimes they raised RuntimeErrors or ArgumentErrors or one of an assortment of custom Meeseeks exceptions.
To combat this, I have added a Meeseeks.Error struct that implements the Exception behaviour and used it throughout the library.
I go into more details about the rationale and implementation in this issue, but the quick takeaway is that this kind of error struct is flexible, plays nicely with pattern matching in places like case and with, and makes it easier to provide useful errors to users.
This is a breaking change because it modifies the returned or raised type of errors. If your Meeseeks-related code handles {:error, ???} or catches one of the old Meeseeks exception types, you will need to make changes.
I apologize for the inconvenience, but this change should lead to safer, more friendly code in the future.
Meeseeks.fetch_all and Meeseeks.fetch_one
The more that I use Elixir in anger, the more I appreciate functions that return {:ok, ...} or {:error, ...}.
In light of the feedback I received on this issue I decided to add Meeseeks.fetch_all and Meeseeks.fetch_one which work like Meeseeks.all and Meeseeks.one respectively, but wrap the result in {:ok, ...} if there is a match or return {:error, %Meeseeks.Error{type: :select, reason: :no_match}} if there is not.
Now itās easier to write code like:
with({:ok, qt} <- Meeseeks.fetch_one(doc, css(".qt"))) do
...
else
{:error, %Meeseeks.Error{type: :select, reason: :no_match}} ->
...
end
My thanks to those who provided feedback.
Other
A bug related to Meeseeks.html was fixed, see this issue for more details