move ifc file handling logic to ifcopenshell.file

to reuse the same logic for both ifcopenshell.open and ifcopenshell.file.from_string()

src/ifcopenshell-python/ifcopenshell/__init__.py

@@ -103,10 +103,6 @@ try:
 except:
     pass
 
-READ_ERROR = ifcopenshell_wrapper.file_open_status.READ_ERROR
-NO_HEADER = ifcopenshell_wrapper.file_open_status.NO_HEADER
-UNSUPPORTED_SCHEMA = ifcopenshell_wrapper.file_open_status.UNSUPPORTED_SCHEMA
-
 
 class Error(Exception):
     """Error used when a generic problem occurs"""
@@ -162,18 +158,7 @@ def open(path: Union[os.PathLike, str], format: Optional[str] = None, should_str
     if should_stream:
         return stream(path)
     f = ifcopenshell_wrapper.open(str(path.absolute()))
-    if f.good():
-        return file(f)
-    else:
-        exc, msg = {
-            READ_ERROR: (IOError, "Unable to open file for reading"),
-            NO_HEADER: (Error, "Unable to parse IFC SPF header"),
-            UNSUPPORTED_SCHEMA: (
-                SchemaError,
-                "Unsupported schema: %s" % ",".join(f.header.file_schema.schema_identifiers),
-            ),
-        }[f.good().value()]
-        raise exc(msg)
+    return file(f)
 
 
 def create_entity(type, schema="IFC4", *args, **kwargs):

src/ifcopenshell-python/ifcopenshell/file.py

@@ -175,6 +175,10 @@ class Transaction:
 
 file_dict = {}
 
+READ_ERROR = ifcopenshell_wrapper.file_open_status.READ_ERROR
+NO_HEADER = ifcopenshell_wrapper.file_open_status.NO_HEADER
+UNSUPPORTED_SCHEMA = ifcopenshell_wrapper.file_open_status.UNSUPPORTED_SCHEMA
+
 
 class file:
     """Base class for containing IFC files.
@@ -246,6 +250,18 @@ class file:
         else:
             schema = {"IFC4X3": "IFC4X3_ADD2"}.get(schema, schema)
         if f is not None:
+            if not f.good():
+                from . import Error, SchemaError
+
+                exc, msg = {
+                    READ_ERROR: (IOError, "Unable to open file for reading"),
+                    NO_HEADER: (Error, "Unable to parse IFC SPF header"),
+                    UNSUPPORTED_SCHEMA: (
+                        SchemaError,
+                        "Unsupported schema: %s" % ",".join(f.header.file_schema.schema_identifiers),
+                    ),
+                }[f.good().value()]
+                raise exc(msg)
             self.wrapped_data = f
         else:
             args = filter(None, [schema])