Fix encapsulation of plugins

Fixes that triggering "About Python Extensions" action resulted in
python runtime error "TypeError: must be type, not None" when
referencing PySide2.QtWidgets.

To improve encapsulation of plugins, all modules that they loaded
were deleted after their main.py finished running. This breaks
if these modules were accessed later e.g. triggered by actions.

Instead of this hack, ensure encapsulation of plugins by making them
actual Python packages.
Qt Creator's python extension path is added to python's module search
path, and extensions are simply imported as packages.
The python extension's main.py simply becomes a standard python
module __init__.py.

This also means that python extensions can depend on, and use other
python extensions' functionality by importing them with "import".

Change-Id: Ibe74c24e337b321007f5fa19c97bd35a5c1f0375
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 55 insertions, 0 deletions

diff --git a/examples/transform/__init__.py b/examples/transform/__init__.py
new file mode 100644
index 0000000..b0d47f1
--- /dev/null
+++ b/examples/transform/__init__.py
@@ -0,0 +1,55 @@
+#############################################################################
+##
+## Copyright (C) 2018 The Qt Company Ltd.
+## Contact: http://www.qt.io/licensing/
+##
+## This file is part of the Python Extensions Plugin for QtCreator.
+##
+## $QT_BEGIN_LICENSE:BSD$
+## You may use this file under the terms of the BSD license as follows:
+##
+## "Redistribution and use in source and binary forms, with or without
+## modification, are permitted provided that the following conditions are
+## met:
+##   * Redistributions of source code must retain the above copyright
+##     notice, this list of conditions and the following disclaimer.
+##   * Redistributions in binary form must reproduce the above copyright
+##     notice, this list of conditions and the following disclaimer in
+##     the documentation and/or other materials provided with the
+##     distribution.
+##   * Neither the name of The Qt Company Ltd nor the names of its
+##     contributors may be used to endorse or promote products derived
+##     from this software without specific prior written permission.
+##
+##
+## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+# This example extension allows you to run a
+# user supplied function that executes on
+# a set of files specified by the user
+
+from PythonExtension import QtCreator
+import actions, ui
+
+def transform():
+    code = ui.getCode()
+    if code[1]:
+        actions.run(code[0])
+
+# Add our new action to the "Tools" menu
+menu = QtCreator.Core.ActionManager.actionContainer("QtCreator.Menu.Tools")
+menu.menu().addAction("Transform files...", transform)