Fix desktop reference counting

Increment the desktop instance's "application reference count" in
Design.__enter__ instead of Design.__init__ to avoid increasing the
reference count incorrectly when, for example, Hfss.set_active_design is
called.

Fixes #4092

pyaedt/application/Design.py

@@ -137,13 +137,14 @@ def __str__(self):
     def __exit__(self, ex_type, ex_value, ex_traceback):
         if ex_type:
             exception_to_desktop(ex_value, ex_traceback)
-        if self._desktop_class._connected_designs > 1:
-            self._desktop_class._connected_designs -= 1
+        if self._desktop_class._connected_app_instances > 1:
+            self._desktop_class._connected_app_instances -= 1
         elif self._desktop_class._initialized_from_design:
             self.release_desktop(self.close_on_exit, self.close_on_exit)
 
     def __enter__(self):
-        pass
+        self._desktop_class._connected_app_instances += 1
+        return self
 
     @pyaedt_function_handler()
     def __getitem__(self, variable_name):
@@ -234,8 +235,6 @@ def load_aedt_thread(path):
             port,
             aedt_process_id,
         )
-        self._desktop_class._connected_designs += 1
-
         self.student_version = self._desktop_class.student_version
         if self.student_version:
             settings.disable_bounding_box_sat = True

pyaedt/circuit.py

@@ -154,9 +154,6 @@ def __init__(
     def _init_from_design(self, *args, **kwargs):
         self.__init__(*args, **kwargs)
 
-    def __enter__(self):
-        return self
-
     def _get_number_from_string(self, stringval):
         value = stringval[stringval.find("=") + 1 :].strip().replace("{", "").replace("}", "").replace(",", ".")
         value = value.replace("µ", "u")

pyaedt/desktop.py

@@ -484,7 +484,7 @@ def __init__(
         self._initialized_from_design = True if Desktop._invoked_from_design else False
         Desktop._invoked_from_design = False
 
-        self._connected_designs = 0
+        self._connected_app_instances = 0
 
         """Initialize desktop."""
         self.launched_by_pyaedt = False

pyaedt/emit.py

@@ -189,10 +189,6 @@ def couplings(self):
         """
         return self._couplings
 
-    @pyaedt_function_handler()
-    def __enter__(self):
-        return self
-
     @pyaedt_function_handler()
     def version(self, detailed=False):
         """

pyaedt/hfss.py

@@ -201,9 +201,6 @@ def __init__(
     def _init_from_design(self, *args, **kwargs):
         self.__init__(*args, **kwargs)
 
-    def __enter__(self):
-        return self
-
     @property
     def field_setups(self):
         """List of AEDT radiation fields.

pyaedt/hfss3dlayout.py

@@ -148,9 +148,6 @@ def __init__(
     def _init_from_design(self, *args, **kwargs):
         self.__init__(*args, **kwargs)
 
-    def __enter__(self):
-        return self
-
     @pyaedt_function_handler()
     def create_edge_port(
         self,

pyaedt/icepak.py

@@ -171,9 +171,6 @@ def __init__(
     def _init_from_design(self, *args, **kwargs):
         self.__init__(*args, **kwargs)
 
-    def __enter__(self):
-        return self
-
     @property
     def problem_type(self):
         """Problem type of the Icepak design. Options are ``"TemperatureAndFlow"``, ``"TemperatureOnly"``,

pyaedt/maxwell.py

@@ -21,9 +21,6 @@
 
 
 class Maxwell(object):
-    def __enter__(self):
-        return self
-
     def __init__(self):
         pass
 

pyaedt/maxwellcircuit.py

@@ -204,6 +204,3 @@ def export_netlist_from_schematic(self, file_to_export):
             return file_to_export
         except:
             return False
-
-    def __enter__(self):
-        return self

pyaedt/mechanical.py

@@ -130,9 +130,6 @@ def __init__(
     def _init_from_design(self, *args, **kwargs):
         self.__init__(*args, **kwargs)
 
-    def __enter__(self):
-        return self
-
     @pyaedt_function_handler()
     def assign_em_losses(
         self,

pyaedt/q3d.py

@@ -82,9 +82,6 @@ def __init__(
         for el in list(self.omatrix.ListReduceMatrixes()):
             self.matrices.append(Matrix(self, el))
 
-    def __enter__(self):
-        return self
-
     @property
     def excitations(self):
         """Get all excitation names.

pyaedt/rmxprt.py

@@ -239,9 +239,6 @@ def __init__(
     def _init_from_design(self, *args, **kwargs):
         self.__init__(*args, **kwargs)
 
-    def __enter__(self):
-        return self
-
     @property
     def design_type(self):
         """Machine design type."""

pyaedt/twinbuilder.py

@@ -563,6 +563,3 @@ def add_q3d_dynamic_component(
         if is_loaded:
             app.close_project(save_project=False)
         return True
-
-    def __enter__(self):
-        return self