Fixed the bug where pdl.__version__ was not set (#882)

It wasn't set previously because importlib searches for the distribution
name and not the module's top-level name. Fallbacks are in place to
revert to searching for 'pdl', and if that fails, it fallsback to the
hardcoded version in _version.py

Signed-off-by: Abi Ullattil <[email protected]>

Author: vite-falcon

src/pdl/__init__.py

@@ -1,6 +1,31 @@
 from importlib.metadata import PackageNotFoundError, version
 
-try:
-    __version__ = version("pdl")
-except PackageNotFoundError:
-    pass
+from ._version import __version__ as hardcoded_version
+
+
+def _get_distribution_version(distribution_name: str) -> str:
+    """
+    This function attempts to retrieve the version of PDL package using
+    importlib.metadata.
+
+    When the package is not installed, importlib will raise a PackageNotFoundError.
+    In this case, we fallback to the hardcoded version.
+
+    When the package is installed, but the distribution name does not match,
+    importlib will return the version of the package that is installed.
+    """
+    try:
+        return version(distribution_name)
+    except PackageNotFoundError:
+        # This is a fallback for when the package is not recognized by importlib.metadata.
+        # This can happen when the package is not installed.
+        return (
+            hardcoded_version
+            if distribution_name == "pdl"
+            else _get_distribution_version(
+                "pdl"  # This is a fallback to maintain the previous behavior.
+            )
+        )
+
+
+__version__ = _get_distribution_version("prompt-declaration-language")

tests/test_lib_version.py

@@ -0,0 +1,16 @@
+import pytest
+
+import pdl
+
+
+def test_version():
+    # Make sure the __version__ attribute is available.
+    assert pdl.__version__ is not None
+
+    # Since pdl is not installed, the version returned will be the dev version.
+    # NOTE: For some reason, the version is not the same as the hardcoded version.
+    assert pdl.__version__.startswith("0.1.dev")
+
+
+if __name__ == "__main__":
+    pytest.main(["-v", "--tb=short", __file__])