[pygobject/wip/jfelder/template-hierarchy-fix: 1/2] gtk overrides: Fix template hierarchy issue

[Jean Felder <jfelder src gnome org>]

commit b5013bf7e127a87cf9f1ab0aef048bf8ef9f46c5
Author: Jean Felder <jfelder src gnome org>
Date:   Thu Mar 19 22:20:37 2020 +0100

    gtk overrides: Fix template hierarchy issue
    
    When a widget is inside a template it is created through a
    g_object_new and does not have a python wrapper when
    pygobject__g_instance_init is called. In that case, a wrapper is
    created and the "__init__" method is called to instantiate it. Then,
    "init_template" is called to init its own template (if it exists).
    
    However, "init_template" needs to be called before the object
    constructor in order to create and instantiate all its children,
    signals and properties.
    
    This issue is fixed by calling init_template before the contructor if
    the python object has been created through g_object_new.
    
    A new test for the template hierarchy is added (based on an example
    from Marinus Schraal).
    
    Closes: #257, #386

 gi/gimodule.c              | 13 ++++++---
 tests/test_gtk_template.py | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+), 4 deletions(-)
---
diff --git a/gi/gimodule.c b/gi/gimodule.c
index f3404583..890a6bfa 100644
--- a/gi/gimodule.c
+++ b/gi/gimodule.c
@@ -1069,6 +1069,7 @@ pygobject__g_instance_init(GTypeInstance   *instance,
     GObject *object = (GObject *) instance;
     PyObject *wrapper, *result;
     PyGILState_STATE state;
+    gboolean needs_init = FALSE;
 
     wrapper = g_object_get_qdata(object, pygobject_wrapper_key);
     if (wrapper == NULL) {
@@ -1095,16 +1096,20 @@ pygobject__g_instance_init(GTypeInstance   *instance,
          * will take the ref */
         pygobject_ref_float ((PyGObject *) wrapper);
 
-        result = PyObject_CallMethod (wrapper, "__init__", NULL);
+        needs_init = TRUE;
+    }
+
+    /* XXX: used for Gtk.Template */
+    if (PyObject_HasAttrString ((PyObject*) Py_TYPE (wrapper), "__dontuse_ginstance_init__")) {
+        result = PyObject_CallMethod (wrapper, "__dontuse_ginstance_init__", NULL);
         if (result == NULL)
             PyErr_Print ();
         else
             Py_DECREF (result);
     }
 
-    /* XXX: used for Gtk.Template */
-    if (PyObject_HasAttrString ((PyObject*) Py_TYPE (wrapper), "__dontuse_ginstance_init__")) {
-        result = PyObject_CallMethod (wrapper, "__dontuse_ginstance_init__", NULL);
+    if (needs_init) {
+        result = PyObject_CallMethod (wrapper, "__init__", NULL);
         if (result == NULL)
             PyErr_Print ();
         else
diff --git a/tests/test_gtk_template.py b/tests/test_gtk_template.py
index d3388b37..69911c81 100644
--- a/tests/test_gtk_template.py
+++ b/tests/test_gtk_template.py
@@ -586,3 +586,73 @@ def test_internal_child():
     child = child.get_children()[0]
     assert isinstance(child, Gtk.Label)
     assert child.props.label == "foo"
+
+
+def test_template_hierarchy():
+    testlabel = """
+    <interface>
+      <template class="TestLabel" parent="GtkLabel">
+      </template>
+     </interface>
+    """
+    @Gtk.Template(string=testlabel)
+    class TestLabel(Gtk.Label):
+
+        __gtype_name__ = "TestLabel"
+
+        def __init__(self):
+            super().__init__()
+            self.props.label = "TestLabel"
+
+    testbox = """
+    <interface>
+      <template class="TestBox" parent="GtkBox">
+        <child>
+          <object class="TestLabel" id="_testlabel"/>
+        </child>
+      </template>
+    </interface>
+    """
+    @Gtk.Template(string=testbox)
+    class TestBox(Gtk.Box):
+
+        __gtype_name__ = "TestBox"
+
+        _testlabel = Gtk.Template.Child()
+
+        def __init__(self):
+            super().__init__()
+
+            assert isinstance(self._testlabel, TestLabel)
+
+    window = """
+    <interface>
+      <template class="MyWindow" parent="GtkWindow">
+        <property name="title">"Hellow World"</property>
+        <child>
+          <object class="TestBox" id="_testbox">
+            <child>
+              <object class="TestLabel" id="_testlabel"/>
+            </child>
+          </object>
+        </child>
+      </template>
+    </interface>
+    """
+    @Gtk.Template(string=window)
+    class MyWindow(Gtk.Window):
+
+        __gtype_name__ = "MyWindow"
+
+        _testbox = Gtk.Template.Child()
+        _testlabel = Gtk.Template.Child()
+
+        def __init__(self):
+            super().__init__()
+
+            assert isinstance(self._testbox, TestBox)
+            assert isinstance(self._testlabel, TestLabel)
+            assert len(self._testbox.get_children()) == 2
+
+    win = MyWindow()
+    assert isinstance(win, MyWindow)