WM: Application Templates

This adds the ability to switch between different application-configurations
without interfering with Blender's normal operation.

This commit doesn't include any templates,
so its mostly to allow collaboration for the Blender 101 project
and other custom configurations.

Application templates can be installed & selected from the file menu.

Other details:

- The `bl_app_template_utils` module handles template activation
  (similar to `addon_utils`).
- The `bl_app_override` module is a general module
  to assist scripts overriding parts of Blender in reversible way.

See docs:
https://docs.blender.org/manual/en/dev/advanced/app_templates.html

See patch: D2565

release/scripts/startup/bl_operators/wm.py

@@ -130,6 +130,20 @@ def execute_context_assign(self, context):
     return operator_path_undo_return(context, data_path)
 
 
+def module_filesystem_remove(path_base, module_name):
+    import os
+    module_name = os.path.splitext(module_name)[0]
+    for f in os.listdir(path_base):
+        f_base = os.path.splitext(f)[0]
+        if f_base == module_name:
+            f_full = os.path.join(path_base, f)
+
+            if os.path.isdir(f_full):
+                os.rmdir(f_full)
+            else:
+                os.remove(f_full)
+
+
 class BRUSH_OT_active_index_set(Operator):
     """Set active sculpt/paint brush from it's number"""
     bl_idname = "brush.active_index_set"
@@ -1917,10 +1931,12 @@ class WM_OT_addon_refresh(Operator):
         return {'FINISHED'}
 
 
+# Note: shares some logic with WM_OT_app_template_install
+# but not enough to de-duplicate. Fixed here may apply to both.
 class WM_OT_addon_install(Operator):
     "Install an add-on"
     bl_idname = "wm.addon_install"
-    bl_label = "Install from File..."
+    bl_label = "Install Add-on from File..."
 
     overwrite = BoolProperty(
             name="Overwrite",
@@ -1951,20 +1967,6 @@ class WM_OT_addon_install(Operator):
             options={'HIDDEN'},
             )
 
-    @staticmethod
-    def _module_remove(path_addons, module):
-        import os
-        module = os.path.splitext(module)[0]
-        for f in os.listdir(path_addons):
-            f_base = os.path.splitext(f)[0]
-            if f_base == module:
-                f_full = os.path.join(path_addons, f)
-
-                if os.path.isdir(f_full):
-                    os.rmdir(f_full)
-                else:
-                    os.remove(f_full)
-
     def execute(self, context):
         import addon_utils
         import traceback
@@ -2017,7 +2019,7 @@ class WM_OT_addon_install(Operator):
 
             if self.overwrite:
                 for f in file_to_extract.namelist():
-                    WM_OT_addon_install._module_remove(path_addons, f)
+                    module_filesystem_remove(path_addons, f)
             else:
                 for f in file_to_extract.namelist():
                     path_dest = os.path.join(path_addons, os.path.basename(f))
@@ -2035,7 +2037,7 @@ class WM_OT_addon_install(Operator):
             path_dest = os.path.join(path_addons, os.path.basename(pyfile))
 
             if self.overwrite:
-                WM_OT_addon_install._module_remove(path_addons, os.path.basename(pyfile))
+                module_filesystem_remove(path_addons, os.path.basename(pyfile))
             elif os.path.exists(path_dest):
                 self.report({'WARNING'}, "File already installed to %r\n" % path_dest)
                 return {'CANCELLED'}
@@ -2070,7 +2072,10 @@ class WM_OT_addon_install(Operator):
         bpy.utils.refresh_script_paths()
 
         # print message
-        msg = tip_("Modules Installed from %r into %r (%s)") % (pyfile, path_addons, ", ".join(sorted(addons_new)))
+        msg = (
+            tip_("Modules Installed (%s) from %r into %r (%s)") %
+            (", ".join(sorted(addons_new)), pyfile, path_addons)
+        )
         print(msg)
         self.report({'INFO'}, msg)
 
@@ -2164,6 +2169,7 @@ class WM_OT_addon_expand(Operator):
 
         return {'FINISHED'}
 
+
 class WM_OT_addon_userpref_show(Operator):
     "Show add-on user preferences"
     bl_idname = "wm.addon_userpref_show"
@@ -2194,6 +2200,124 @@ class WM_OT_addon_userpref_show(Operator):
         return {'FINISHED'}
 
 
+# Note: shares some logic with WM_OT_addon_install
+# but not enough to de-duplicate. Fixes here may apply to both.
+class WM_OT_app_template_install(Operator):
+    "Install an application-template"
+    bl_idname = "wm.app_template_install"
+    bl_label = "Install Template from File..."
+
+    overwrite = BoolProperty(
+            name="Overwrite",
+            description="Remove existing template with the same ID",
+            default=True,
+            )
+
+    filepath = StringProperty(
+            subtype='FILE_PATH',
+            )
+    filter_folder = BoolProperty(
+            name="Filter folders",
+            default=True,
+            options={'HIDDEN'},
+            )
+    filter_python = BoolProperty(
+            name="Filter python",
+            default=True,
+            options={'HIDDEN'},
+            )
+    filter_glob = StringProperty(
+            default="*.py;*.zip",
+            options={'HIDDEN'},
+            )
+
+    def execute(self, context):
+        import addon_utils
+        import traceback
+        import zipfile
+        import shutil
+        import os
+
+        pyfile = self.filepath
+
+        path_app_templates = bpy.utils.user_resource(
+            'SCRIPTS', os.path.join("startup", "bl_app_templates_user"),
+            create=True,
+        )
+
+        if not path_app_templates:
+            self.report({'ERROR'}, "Failed to get add-ons path")
+            return {'CANCELLED'}
+
+        if not os.path.isdir(path_app_templates):
+            try:
+                os.makedirs(path_app_templates, exist_ok=True)
+            except:
+                traceback.print_exc()
+
+        app_templates_old = set(os.listdir(path_app_templates))
+
+        # check to see if the file is in compressed format (.zip)
+        if zipfile.is_zipfile(pyfile):
+            try:
+                file_to_extract = zipfile.ZipFile(pyfile, 'r')
+            except:
+                traceback.print_exc()
+                return {'CANCELLED'}
+
+            if self.overwrite:
+                for f in file_to_extract.namelist():
+                    module_filesystem_remove(path_app_templates, f)
+            else:
+                for f in file_to_extract.namelist():
+                    path_dest = os.path.join(path_app_templates, os.path.basename(f))
+                    if os.path.exists(path_dest):
+                        self.report({'WARNING'}, "File already installed to %r\n" % path_dest)
+                        return {'CANCELLED'}
+
+            try:  # extract the file to "bl_app_templates_user"
+                file_to_extract.extractall(path_app_templates)
+            except:
+                traceback.print_exc()
+                return {'CANCELLED'}
+
+        else:
+            path_dest = os.path.join(path_app_templates, os.path.basename(pyfile))
+
+            if self.overwrite:
+                module_filesystem_remove(path_app_templates, os.path.basename(pyfile))
+            elif os.path.exists(path_dest):
+                self.report({'WARNING'}, "File already installed to %r\n" % path_dest)
+                return {'CANCELLED'}
+
+            # if not compressed file just copy into the addon path
+            try:
+                shutil.copyfile(pyfile, path_dest)
+            except:
+                traceback.print_exc()
+                return {'CANCELLED'}
+
+        app_templates_new = set(os.listdir(path_app_templates)) - app_templates_old
+
+        # in case a new module path was created to install this addon.
+        bpy.utils.refresh_script_paths()
+
+        # print message
+        msg = (
+            tip_("Template Installed (%s) from %r into %r") %
+            (", ".join(sorted(app_templates_new)), pyfile, path_app_templates)
+        )
+        print(msg)
+        self.report({'INFO'}, msg)
+
+        return {'FINISHED'}
+
+    def invoke(self, context, event):
+        wm = context.window_manager
+        wm.fileselect_add(self)
+        return {'RUNNING_MODAL'}
+
+
 classes = (
     BRUSH_OT_active_index_set,
     WM_OT_addon_disable,
@@ -2203,6 +2327,7 @@ classes = (
     WM_OT_addon_refresh,
     WM_OT_addon_remove,
     WM_OT_addon_userpref_show,
+    WM_OT_app_template_install,
     WM_OT_appconfig_activate,
     WM_OT_appconfig_default,
     WM_OT_blenderplayer_start,
@@ -2246,4 +2371,4 @@ classes = (
     WM_OT_sysinfo,
     WM_OT_theme_install,
     WM_OT_url_open,
-)
+)