cq_toplevel: memoize the model, to speed up the case where invoked in a way that we dont need to compute it

cq_toplevel.py

@@ -44,7 +44,8 @@ def svg_export_options(view: str):
         showHidden = True,
     )
 
-def model():
+def _model():
+    logger.info("computing model ...")
     render_phone = os.environ.get("CASE_RENDER_PHONE", "") not in ("", "0")
     render_phone_only = os.environ.get("CASE_RENDER_PHONE_ONLY", "") not in ("", "0")
 
@@ -56,6 +57,14 @@ def model():
     battery = ldtek_battery.LdtekBattery()
     return case.case(phone, battery=battery, render_phone=render_phone)
 
+_computedModel = None
+def model():
+    """ memoized wrapper around `_model` """
+    global _computedModel
+    if _computedModel is None:
+        _computedModel = _model()
+    return _computedModel
+
 def main():
     logging.basicConfig()
     logging.getLogger().setLevel(logging.INFO)
@@ -76,12 +85,9 @@ def main():
     if args.render_phone_only:
         os.environ["CASE_RENDER_PHONE_ONLY"] = "1"
 
-    logger.info("computing model ...")
-    model_ = model()
-
     if args.export_stl:
         logger.info("exporting stl to %s", args.export_stl)
-        cq.exporters.export(model_, args.export_stl)
+        cq.exporters.export(model(), args.export_stl)
 
     if args.export_svg:
         view = None
@@ -92,14 +98,14 @@ def main():
         elif "right" in args.export_svg:
             view = "right"
         logger.info("exporting svg to %s (view: %s)", args.export_svg, str(view))
-        cq.exporters.export(model_, args.export_svg, opt=svg_export_options(view))
+        cq.exporters.export(model(), args.export_svg, opt=svg_export_options(view))
 
     if args.export_vtk:
         vtk_file = args.export_vtk
         js_var, _ext = os.path.splitext(os.path.basename(vtk_file))
         js_file = f'{vtk_file}.js'
         logger.info("exporting VTK (for web rendering) to %s", vtk_file)
-        cq.exporters.export(model_, vtk_file, cq.exporters.ExportTypes.VTP)
+        cq.exporters.export(model(), vtk_file, cq.exporters.ExportTypes.VTP)
 
         logger.info("wrapping VTK data in a javascript variable (var %s) in %s", js_var, js_file)
         vtk_data = open(vtk_file).read()
@@ -116,4 +122,6 @@ def main():
 if __name__ == "__main__":
     main()
 else:
+    # this `result` var should be picked up by cadquery, in case we were imported by it.
+    # note that we don't actually get here until the user presses the `>` render button.
     result = model()