instance_exec to the rescue

lib/filterer/base.rb

@@ -199,7 +199,7 @@ def order_by_sort_option(opt)
     def sort_proc_to_string(opt)
       sort_key = opt[:key]
       matches = sort_key.is_a?(Regexp) && params[:sort].match(sort_key)
-      opt[:string_or_proc].call(matches)
+      instance_exec matches, &opt[:string_or_proc]
     end
 
     def default_sort_option

lib/filterer/version.rb

@@ -1,3 +1,3 @@
 module Filterer
-  VERSION = '1.0.0.beta.3'
+  VERSION = '1.0.0.beta.4'
 end

spec/lib/filterer/base_spec.rb

@@ -107,13 +107,20 @@ def starting_query
     FakeQuery.new
   end
 
+  def something_important
+    'yeehaw'
+  end
+
   sort_option 'id', default: true
   sort_option Regexp.new('foo([0-9]+)'), -> (matches) { matches[1] }
   sort_option Regexp.new('zoo([0-9]+)'), -> (matches) {
     if matches[1].to_i > 10
       'zoo'
     end
   }
+  sort_option 'context', -> (_matches) {
+    something_important
+  }
 end
 
 class SortingFiltererF < SortingFiltererE
@@ -248,6 +255,11 @@ class PaginationFiltererInherit < PaginationFiltererB
       filterer = SortingFiltererF.new(sort: 'zoo111')
     end
 
+    it 'calls with context' do
+      expect_any_instance_of(FakeQuery).to receive(:order).with('yeehaw asc , tiebreak').and_return(FakeQuery.new)
+      filterer = SortingFiltererF.new(sort: 'context')
+    end
+
     it 'applies the default sort if the proc returns nil' do
       allow_any_instance_of(FakeQuery).to(
         receive_message_chain(:model, :table_name).