src/Pure/Thy/file_format.scala

--- a/src/Pure/Thy/file_format.scala	Tue Apr 07 22:13:22 2020 +0200
+++ b/src/Pure/Thy/file_format.scala	Wed Apr 08 13:14:05 2020 +0200
@@ -12,12 +12,12 @@
   sealed case class Theory_Context(name: Document.Node.Name, content: String)
 
 
-  /* environment */
+  /* registry */
 
-  def environment(): Environment =
-    new Environment(Isabelle_System.init_classes[File_Format]("ISABELLE_FILE_FORMATS"))
+  lazy val registry: Registry =
+    new Registry(Isabelle_System.services.collect { case c: File_Format => c })
 
-  final class Environment private [File_Format](file_formats: List[File_Format])
+  final class Registry private [File_Format](file_formats: List[File_Format])
   {
     override def toString: String = file_formats.mkString("File_Format.Environment(", ",", ")")
 
@@ -53,7 +53,7 @@
   object No_Agent extends Agent
 }
 
-trait File_Format
+trait File_Format extends Isabelle_System.Service
 {
   def format_name: String
   override def toString: String = format_name