lib/shoes/swt/generate_backend.rb in shoes-swt-4.0.0.pre7 vs lib/shoes/swt/generate_backend.rb in shoes-swt-4.0.0.pre8

@@ -1,7 +1,38 @@
+# frozen_string_literal: true
+
 require 'rbconfig'
 
-def generate_backend(path)
-  options = "-J-XstartOnFirstThread" if RbConfig::CONFIG["host_os"] =~ /darwin/
+class Shoes
+  module SelectedBackend
+    class << self
+      def validate
+        if RUBY_ENGINE != "jruby"
+          puts <<-EOS
 
-  "jruby #{options} #{path}/shoes-swt"
+*******************************************************************************
+The shoes-swt backend requires a 9.X version of JRuby.
+
+You are running the following Ruby instead:
+
+  #{RUBY_DESCRIPTION}
+
+Please download JRuby from http://jruby.org (or your favorite Ruby version
+manager), then check our https://github.com/shoes/shoes4#installing-shoes-4 to
+get Shoes installed.
+
+Sorry for the inconvenience!
+*******************************************************************************
+
+EOS
+          exit 1
+        end
+      end
+
+      def generate(path)
+        options = "-J-XstartOnFirstThread" if RbConfig::CONFIG["host_os"] =~ /darwin/
+
+        "jruby #{options} #{path}/shoes-swt"
+      end
+    end
+  end
 end