update sentry.eventfilter docs

Author: mitchellhenke

lib/sentry.ex

@@ -84,7 +84,7 @@ defmodule Sentry do
       {:ok, another_event_id} = Sentry.capture_exception(other_exception, [event_source: :my_source, result: :sync])
 
   ### Options
-    * `:event_source` - The source passed as the first argument to `Sentry.EventFilter.exclude_exception?/2`
+    * `:event_source` - The source passed as the first argument to `c:Sentry.EventFilter.exclude_exception?/2`
 
   ## Configuring The `Logger` Backend
 

lib/sentry/event_filter.ex

@@ -1,13 +1,26 @@
 defmodule Sentry.EventFilter do
-  @moduledoc false
+  @moduledoc """
+  This module defines a Behaviour for filtering Sentry events.
+  There is one callback to implement. The first argument will be
+  the exception reported, and the second is the source. Events
+  from `Sentry.Plug` will have :plug as a source, `Sentry.Phoenix.Endpoint`
+  will have `:endpoint` and events from `Sentry.LoggerBackend` will have
+  `:logger` as the source. A custom source can also be specified by passing
+  the `event_source` option to `Sentry.capture_exception/2`.
 
-  @callback exclude_exception?(Exception.t(), atom) :: any
-end
+  As an example, if you wanted to exclude any `ArithmeticError` exceptions:
 
-defmodule Sentry.DefaultEventFilter do
-  @behaviour Sentry.EventFilter
+      defmodule MyApp.SentryEventFilter do
+        @behaviour Sentry.EventFilter
 
-  @moduledoc false
+        def exclude_exception?(%ArithmeticError{}, _source), do: true
+        def exclude_exception?(_exception, _source), do: false
+      end
+  """
 
-  def exclude_exception?(_, _), do: false
+  @doc """
+  Callback that returns whether an exception should be excluded from
+  being reported
+  """
+  @callback exclude_exception?(Exception.t(), atom) :: boolean
 end