language: Use new extern syntax in signal handlers

blueprintcompiler/language/gobject_signal.py

@@ -33,6 +33,7 @@ class Signal(AstNode):
             ]
         ),
         "=>",
+        Optional(["$", UseLiteral("extern", True)]),
         UseIdent("handler").expected("the name of a function to handle the signal"),
         Match("(").expected("argument list"),
         Optional(UseIdent("object")).expected("object identifier"),
@@ -78,6 +79,14 @@ class Signal(AstNode):
     def gir_class(self):
         return self.parent.parent.gir_class
 
+    @validate("handler")
+    def old_extern(self):
+        if not self.tokens["extern"]:
+            raise UpgradeWarning(
+                "Use the '$' extern syntax introduced in blueprint 0.8.0",
+                actions=[CodeAction("Use '$' syntax", "$" + self.tokens["handler"])],
+            )
+
     @validate("name")
     def signal_exists(self):
         if self.gir_class is None or isinstance(self.gir_class, UncheckedType):
@@ -116,7 +125,7 @@ def decompile_signal(ctx, gir, name, handler, swapped="false", object=None):
     object_name = object or ""
     name = name.replace("_", "-")
     if decompile.truthy(swapped):
-        ctx.print(f"{name} => {handler}({object_name}) swapped;")
+        ctx.print(f"{name} => ${handler}({object_name}) swapped;")
     else:
-        ctx.print(f"{name} => {handler}({object_name});")
+        ctx.print(f"{name} => ${handler}({object_name});")
     return gir

tests/sample_errors/signal_dne.blp

@@ -1,5 +1,5 @@
 using Gtk 4.0;
 
 Button {
-  eaten-by-velociraptors => on_eaten_by_velociraptors();
+  eaten-by-velociraptors => $on_eaten_by_velociraptors();
 }

tests/sample_errors/signal_object_dne.blp

@@ -1,5 +1,5 @@
 using Gtk 4.0;
 
 Button {
-    clicked => function(dinosaur);
+    clicked => $function(dinosaur);
 }

tests/sample_errors/signal_object_dne.err

@@ -1 +1 @@
-4,25,8,Could not find object with ID 'dinosaur'
+4,26,8,Could not find object with ID 'dinosaur'

tests/sample_errors/warn_old_extern.blp

@@ -2,4 +2,5 @@ using Gtk 4.0;
 
 .MyClass {
   prop: typeof(.MyOtherClass);
+  clicked => handler();
 }

tests/sample_errors/warn_old_extern.err

@@ -1,2 +1,3 @@
 3,1,8,Use the '$' extern syntax introduced in blueprint 0.8.0
 4,16,13,Use the '$' extern syntax introduced in blueprint 0.8.0
+5,14,7,Use the '$' extern syntax introduced in blueprint 0.8.0

tests/samples/signal.blp

@@ -1,10 +1,10 @@
 using Gtk 4.0;
 
 Entry {
-  activate => click(button);
+  activate => $click(button);
 }
 
 Button button {
-  clicked => on_button_clicked() swapped;
-  notify::visible => on_button_notify_visible();
+  clicked => $on_button_clicked() swapped;
+  notify::visible => $on_button_notify_visible();
 }

tests/samples/template.blp

@@ -2,7 +2,7 @@ using Gtk 4.0;
 
 template TestTemplate : ApplicationWindow {
   test-property: "Hello, world";
-  test-signal => on_test_signal();
+  test-signal => $on_test_signal();
 }
 
 Dialog {