From 3c7c939c1ec0e0f1d7fb3cb1267a06614104ef22 Mon Sep 17 00:00:00 2001
From: Corin Langosch <info@corinlangosch.com>
Date: Tue, 15 May 2018 20:34:59 +0200
Subject: [PATCH 1/3] Allow email_prefix to be a proc

---
 README.md                                      |  4 ++--
 lib/exception_notifier/email_notifier.rb       |  2 +-
 test/exception_notifier/email_notifier_test.rb | 15 +++++++++++++++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index f5a1ee26..4345ba8a 100644
--- a/README.md
+++ b/README.md
@@ -182,9 +182,9 @@ Who the message is destined for, can be a string of addresses, an array of addre
 
 ##### email_prefix
 
-*String, default: [ERROR]*
+*String/Proc, default: [ERROR]*
 
-The subject's prefix of the message.
+The subject's prefix of the message. It can be a proc that returns a string. The proc will be evaluated when the mail is sent.
 
 ##### sections
 
diff --git a/lib/exception_notifier/email_notifier.rb b/lib/exception_notifier/email_notifier.rb
index d5a68ddc..39bd2080 100644
--- a/lib/exception_notifier/email_notifier.rb
+++ b/lib/exception_notifier/email_notifier.rb
@@ -59,7 +59,7 @@ def background_exception_notification(exception, options={}, default_options={})
           private
 
           def compose_subject
-            subject = "#{@options[:email_prefix]}"
+            subject = "#{maybe_call(@options[:email_prefix])}"
             subject << "(#{@options[:accumulated_errors_count]} times)" if @options[:accumulated_errors_count].to_i > 1
             subject << "#{@kontroller.controller_name} #{@kontroller.action_name}" if @kontroller && @options[:include_controller_and_action_names_in_subject]
             subject << " (#{@exception.class})"
diff --git a/test/exception_notifier/email_notifier_test.rb b/test/exception_notifier/email_notifier_test.rb
index 442f258c..a0e552a3 100644
--- a/test/exception_notifier/email_notifier_test.rb
+++ b/test/exception_notifier/email_notifier_test.rb
@@ -219,6 +219,21 @@ class EmailNotifierTest < ActiveSupport::TestCase
     assert_equal %w{second@example.com}, mail.to
   end
 
+  test "should lazily evaluate email_prefix" do
+    email_prefixes = %w(first second)
+    email_notifier = ExceptionNotifier::EmailNotifier.new(
+      :email_prefix => -> { email_prefixes.shift },
+      :sender_address => %{"Dummy Notifier" <dummynotifier@example.com>},
+      :exception_recipients => "test@exampke.com",
+      :delivery_method => :test,
+    )
+
+    mail = email_notifier.call(@exception)
+    assert_equal %|first (ZeroDivisionError) "divided by 0"|, mail.subject
+    mail = email_notifier.call(@exception)
+    assert_equal %|second (ZeroDivisionError) "divided by 0"|, mail.subject
+  end
+
   test "should prepend accumulated_errors_count in email subject if accumulated_errors_count larger than 1" do
     ActionMailer::Base.deliveries.clear
 

From b80ce40117710338b7e68106488a83be31c188aa Mon Sep 17 00:00:00 2001
From: Corin Langosch <info@corinlangosch.com>
Date: Wed, 16 May 2018 22:06:23 +0200
Subject: [PATCH 2/3] Pass reference to exception notifier blocks

---
 lib/exception_notifier/email_notifier.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/exception_notifier/email_notifier.rb b/lib/exception_notifier/email_notifier.rb
index 39bd2080..2a39cbd3 100644
--- a/lib/exception_notifier/email_notifier.rb
+++ b/lib/exception_notifier/email_notifier.rb
@@ -130,7 +130,8 @@ def load_custom_views
           end
 
           def maybe_call(maybe_proc)
-            maybe_proc.respond_to?(:call) ? maybe_proc.call : maybe_proc
+            return maybe_proc unless maybe_proc.respond_to?(:call)
+            (maybe_proc.arity == 0) ? maybe_proc.call : maybe_proc.call(self)
           end
         end
       end

From 0c07ea649dfd0afa8c1590316bc4185e9d867a08 Mon Sep 17 00:00:00 2001
From: Corin Langosch <info@corinlangosch.com>
Date: Wed, 16 May 2018 22:14:28 +0200
Subject: [PATCH 3/3] Adds access to some notifier variables in blocks

---
 lib/exception_notifier/email_notifier.rb | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/exception_notifier/email_notifier.rb b/lib/exception_notifier/email_notifier.rb
index 2a39cbd3..412dbcc1 100644
--- a/lib/exception_notifier/email_notifier.rb
+++ b/lib/exception_notifier/email_notifier.rb
@@ -20,6 +20,8 @@ def method_missing(*args, &block)
 
       def self.extended(base)
         base.class_eval do
+          attr_reader :env, :exception, :request, :data
+
           self.send(:include, ExceptionNotifier::BacktraceCleaner)
 
           # Append application view path to the ExceptionNotifier lookup context.