Store Livecheck#version as symbol or string

Library/Homebrew/livecheck.rb

@@ -106,22 +106,12 @@ class Livecheck
 
   # TODO: documentation
   def version(val = nil)
-    @version = case val
-    when nil
-      return @version
-    when :before_comma
-      [",", :first]
-    when :after_comma
-      [",", :second]
-    when :before_colon
-      [":", :first]
-    when :after_colon
-      [":", :second]
-    when String
-      val
-    else
+    return @version if val.nil?
+    unless val.is_a?(String) || (val.is_a?(Symbol) && Cask::DSL::Version.method_defined?(val))
       raise TypeError, "Livecheck#version expects a String or valid Symbol"
     end
+
+    @version = val
   end
 
   # Returns a `Hash` of all instance variable values.

Library/Homebrew/livecheck/livecheck.rb

@@ -125,6 +125,8 @@ module Homebrew
             else
               formula.stable.version
             end
+        elsif livecheck_version.is_a?(Symbol)
+          Version.new(Cask::DSL::Version.new(formula_or_cask.version).try(livecheck_version))
           else
             Version.new(formula_or_cask.version)
         end

Library/Homebrew/test/livecheck_spec.rb

@@ -117,7 +117,7 @@ describe Livecheck do
       expect(livecheckable.version).to eq("1.2.3")
 
       livecheckable.version(:before_comma)
-      expect(livecheckable.version).to eq([",", :first])
+      expect(livecheckable.version).to eq(:before_comma)
     end
 
     it "raises a TypeError if the argument isn't a String or Symbol" do