decompiler: Fix bug in signals with template object

If a signal handler had the template as its object, the decompiler would
output the class name instead of the 'template' keyword.

blueprintcompiler/language/gobject_signal.py

@@ -225,8 +225,14 @@ class Signal(AstNode):
 
 
 @decompiler("signal")
-def decompile_signal(ctx, gir, name, handler, swapped=None, after="false", object=None):
+def decompile_signal(
+    ctx: DecompileCtx, gir, name, handler, swapped=None, after="false", object=None
+):
     object_name = object or ""
+
+    if object_name == ctx.template_class:
+        object_name = "template"
+
     name = name.replace("_", "-")
     line = f"{name} => ${handler}({object_name})"
 

tests/samples/signal_template_object.blp

@@ -0,0 +1,7 @@
+using Gtk 4.0;
+
+template $MyTemplate {
+  Button {
+    clicked => $my_signal_handler(template);
+  }
+}

tests/samples/signal_template_object.ui

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <template class="MyTemplate">
+    <child>
+      <object class="GtkButton">
+        <signal name="clicked" handler="my_signal_handler" object="MyTemplate"/>
+      </object>
+    </child>
+  </template>
+</interface>

tests/test_samples.py

@@ -198,6 +198,7 @@ class TestSamples(unittest.TestCase):
                 "parseable",
                 "signal",
                 "signal_not_swapped",
+                "signal_template_object",
                 "template",
                 "template_binding",
                 "template_binding_extern",