Merge pull request #489 from mattgibbs/deferred_connections

Defer connections until after PyDMMainWindow loads the display.

pydm/application.py

@@ -360,7 +360,7 @@ def load_py_file(self, pyfile, args=None, macros=None):
             kwargs['macros'] = macros
         return cls(**kwargs)
 
-    def open_file(self, ui_file, macros=None, command_line_args=None, **kwargs):
+    def open_file(self, ui_file, macros=None, command_line_args=None, defer_connections=False, **kwargs):
         """
         Open a .ui or .py file, and return a widget from the loaded file.
         This method is the entry point for all opening of new displays,
@@ -401,7 +401,7 @@ def open_file(self, ui_file, macros=None, command_line_args=None, **kwargs):
         merged_macros = self.macro_stack[-1].copy()
         merged_macros.update(macros)
         self.macro_stack.append(merged_macros)
-        with data_plugins.connection_queue():
+        with data_plugins.connection_queue(defer_connections=defer_connections):
             if extension == '.ui':
                 widget = self.load_ui_file(filepath, merged_macros)
             elif extension == '.py':

pydm/data_plugins/__init__.py

@@ -11,7 +11,7 @@
 import uuid
 from collections import deque
 from contextlib import contextmanager
-
+from qtpy.QtWidgets import QApplication
 from .plugin import PyDMPlugin
 from ..utilities import protocol_and_address
 from .. import config
@@ -21,25 +21,39 @@
 __read_only = False
 global __CONNECTION_QUEUE__
 __CONNECTION_QUEUE__ = None
+global __DEFER_CONNECTIONS__
+__DEFER_CONNECTIONS__ = False
 
 @contextmanager
-def connection_queue():
+def connection_queue(defer_connections=False):
     global __CONNECTION_QUEUE__
+    global __DEFER_CONNECTIONS__
     if __CONNECTION_QUEUE__ is None:
         __CONNECTION_QUEUE__ = deque()
+        __DEFER_CONNECTIONS__ = defer_connections
+    yield
+    if __DEFER_CONNECTIONS__:
+        return
+    establish_queued_connections()
+
+def establish_queued_connections():
+    global __DEFER_CONNECTIONS__
+    global __CONNECTION_QUEUE__
+    if __CONNECTION_QUEUE__ is None:
+        return
     try:
-        yield
-        if __CONNECTION_QUEUE__ is None:
-            return
         while not len(__CONNECTION_QUEUE__) == 0:
-            channel = __CONNECTION_QUEUE__.pop()
+            channel = __CONNECTION_QUEUE__.popleft()
             establish_connection_immediately(channel)
+            QApplication.instance().processEvents()
     finally:
         __CONNECTION_QUEUE__ = None
+        __DEFER_CONNECTIONS__ = False
+
 
 def establish_connection(channel):
     global __CONNECTION_QUEUE__
-    if __CONNECTION_QUEUE__:
+    if __CONNECTION_QUEUE__ is not None:
         __CONNECTION_QUEUE__.append(channel)
     else:
         establish_connection_immediately(channel)

pydm/main_window.py

@@ -140,7 +140,7 @@ def open_abs_file(self, filename, macros=None, command_line_args=None):
         if command_line_args is None:
             command_line_args = []
         merged_macros = self.merge_with_current_macros(macros)
-        widget = self.app.open_file(filename, merged_macros, command_line_args)
+        widget = self.app.open_file(filename, merged_macros, command_line_args, defer_connections=True)
         if (len(self.back_stack) == 0) or (self.current_file() != filename):
             self.back_stack.append((filename, merged_macros, command_line_args))
         self.set_display_widget(widget)
@@ -160,6 +160,7 @@ def open_abs_file(self, filename, macros=None, command_line_args=None):
         self.ui.actionEdit_in_Designer.setText(edit_in_text)
         if self.designer_path:
             self.ui.actionEdit_in_Designer.setEnabled(True)
+        data_plugins.establish_queued_connections()
 
     def new_window(self, ui_file, macros=None, command_line_args=None):
         filename = self.join_to_current_file_path(ui_file)

pydm/widgets/template_repeater.py

@@ -328,7 +328,7 @@ def rebuild(self):
                 QWidget().setLayout(self.layout())
             l = layout_class(self)
             self.setLayout(l)
-        with pydm.data_plugins.connection_queue():
+        with pydm.data_plugins.connection_queue(defer_connections=True):
             for i, variables in enumerate(self.data):
                 if is_qt_designer() and i > self.countShownInDesigner - 1:
                     break
@@ -339,6 +339,7 @@ def rebuild(self):
                 w.setParent(self)
                 self.layout().addWidget(w)
         self.setUpdatesEnabled(True)
+        pydm.data_plugins.establish_queued_connections()
 
     def clear(self):
         """ Clear out any existing instances of the template inside