meta pkg: wrap imports for traceability (#13924)

.actions/setup_tools.py

@@ -270,6 +270,37 @@ def prune_comments_docstrings(lines: List[str]) -> List[str]:
     return body
 
 
+def wrap_try_except(body: List[str], pkg: str, ver: str) -> List[str]:
+    """Wrap the file with try/except for better traceability of import misalignment."""
+    not_empty = sum(1 for ln in body if ln)
+    if not_empty == 0:
+        return body
+    body = ["try:"] + [f"    {ln}" if ln else "" for ln in body]
+    body += [
+        "",
+        "except ImportError as err:",
+        "",
+        "    from os import linesep",
+        f"    from {pkg} import __version__",
+        f"    msg = f'Your `lightning` package was built for `{pkg}=={ver}`," + " but you are running {__version__}'",
+        "    raise type(err)(str(err) + linesep + msg)",
+    ]
+    return body
+
+
+def parse_version_from_file(pkg_root: str) -> str:
+    """Loading the package version from file."""
+    file_ver = os.path.join(pkg_root, "__version__.py")
+    file_about = os.path.join(pkg_root, "__about__.py")
+    if os.path.isfile(file_ver):
+        ver = _load_py_module("version", file_ver).version
+    elif os.path.isfile(file_about):
+        ver = _load_py_module("about", file_about).__version__
+    else:  # this covers case you have build only meta-package so not additional source files are present
+        ver = ""
+    return ver
+
+
 def create_meta_package(src_folder: str, pkg_name: str = "pytorch_lightning", lit_name: str = "pytorch"):
     """Parse the real python package and for each module create a mirroe version with repalcing all function and
     class implementations by cross-imports to the true package.
@@ -279,6 +310,7 @@ def create_meta_package(src_folder: str, pkg_name: str = "pytorch_lightning", li
     >>> create_meta_package(os.path.join(_PROJECT_ROOT, "src"))
     """
     package_dir = os.path.join(src_folder, pkg_name)
+    pkg_ver = parse_version_from_file(package_dir)
     # shutil.rmtree(os.path.join(src_folder, "lightning", lit_name))
     py_files = glob.glob(os.path.join(src_folder, pkg_name, "**", "*.py"), recursive=True)
     for py_file in py_files:
@@ -310,15 +342,16 @@ def create_meta_package(src_folder: str, pkg_name: str = "pytorch_lightning", li
             while body_len != len(body):
                 body_len = len(body)
                 body = prune_empty_statements(body)
-            # TODO: add try/catch wrapper for whole body,
+            # add try/catch wrapper for whole body,
             #  so when import fails it tells you what is the package version this meta package was generated for...
+            body = wrap_try_except(body, pkg_name, pkg_ver)
 
         # todo: apply pre-commit formatting
         body = [ln for ln, _group in groupby(body)]
         lines = []
         # drop duplicated lines
         for ln in body:
-            if ln + os.linesep not in lines or ln in (")", ""):
+            if ln + os.linesep not in lines or ln.lstrip() in (")", ""):
                 lines.append(ln + os.linesep)
         # compose the target file name
         new_file = os.path.join(src_folder, "lightning", lit_name, local_path)