New experimental option to export file from memory in preparation for incremental editing

src/ifcblenderexport/blenderbim/bim/export_ifc.py

@@ -1345,6 +1345,9 @@ class IfcExporter:
         self.roundtrip_id_new_to_old = {}
 
     def export(self, selected_objects):
+        self.file = ifc.IfcStore.get_file()
+        if self.file and self.ifc_export_settings.should_export_from_memory:
+            return self.write_ifc_file()
         self.schema_version = self.ifc_export_settings.schema
         self.schema = ifcopenshell.ifcopenshell_wrapper.schema_by_name(self.schema_version)
         self.file = ifcopenshell.file(schema=self.schema_version)
@@ -3526,6 +3529,7 @@ class IfcExportSettings:
         ]
         self.should_use_presentation_style_assignment = False
         self.should_guess_quantities = False
+        self.should_export_from_memory = False
         self.context_tree = []
 
     @staticmethod
@@ -3545,6 +3549,7 @@ class IfcExportSettings:
         settings.should_force_faceted_brep = scene_bim.export_should_force_faceted_brep
         settings.should_force_triangulation = scene_bim.export_should_force_triangulation
         settings.should_roundtrip_native = scene_bim.import_export_should_roundtrip_native
+        settings.should_export_from_memory = scene_bim.export_should_export_from_memory
         settings.context_tree = []
         for ifc_context in ["model", "plan"]:
             if getattr(scene_bim, "has_{}_context".format(ifc_context)):

src/ifcblenderexport/blenderbim/bim/ifc.py

@@ -12,5 +12,6 @@ class IfcStore:
     def get_file():
         if IfcStore.file is None:
             IfcStore.path = bpy.context.scene.BIMProperties.ifc_file
-            IfcStore.file = ifcopenshell.open(IfcStore.path)
+            if IfcStore.path:
+                IfcStore.file = ifcopenshell.open(IfcStore.path)
         return IfcStore.file

src/ifcblenderexport/blenderbim/bim/prop.py

@@ -1263,6 +1263,7 @@ class BIMProperties(PropertyGroup):
     )
     export_should_force_faceted_brep: BoolProperty(name="Export with Faceted Breps", default=False)
     export_should_force_triangulation: BoolProperty(name="Export with Triangulation", default=False)
+    export_should_export_from_memory: BoolProperty(name="Export from Memory", default=False)
     import_should_ignore_site_coordinates: BoolProperty(name="Import Ignoring Site Coordinates", default=False)
     import_should_ignore_building_coordinates: BoolProperty(name="Import Ignoring Building Coordinates", default=False)
     import_should_reset_absolute_coordinates: BoolProperty(name="Import Resetting Absolute Coordinates", default=False)

src/ifcblenderexport/blenderbim/bim/ui.py

@@ -1888,6 +1888,8 @@ class BIM_PT_mvd(Panel):
         row = layout.row()
         row.prop(bim_properties, "import_export_should_roundtrip_native")
         row = layout.row()
+        row.prop(bim_properties, "export_should_export_from_memory")
+        row = layout.row()
         row.prop(bim_properties, "import_should_use_cpu_multiprocessing")
         row = layout.row()
         row.prop(bim_properties, "import_should_import_with_profiling")