chore: change project structure

.gitignore

@@ -138,4 +138,4 @@ temp.py
 # Pyannotate generated stubs
 type_info.json
 .pdm-build/
-src/pdm/models/VERSION
+src/pdm/VERSION

news/3155.misc.md

@@ -0,0 +1 @@
+Change the project structure to a normal package from a namespace package.

pyproject.toml

@@ -76,7 +76,7 @@ pdm = "pdm.core:main"
 
 [tool.pdm.version]
 source = "scm"
-write_to = "pdm/models/VERSION"
+write_to = "pdm/VERSION"
 
 [tool.pdm.build]
 excludes = ["./**/.git"]
@@ -221,12 +221,12 @@ ignore-words-list = "ba,overriden,te"
 
 [tool.coverage.run]
 branch = true
-source = ["pdm/"]
+source = ["pdm"]
 omit = [
-    "pdm/__main__.py",
-    "pdm/pep582/sitecustomize.py",
-    "pdm/models/in_process/*.py",
-    "pdm/models/setup.py",
+    "*/pdm/__main__.py",
+    "*/pdm/pep582/sitecustomize.py",
+    "*/pdm/models/in_process/*.py",
+    "*/pdm/models/setup.py",
     "*/pdm-test-*-env/*",
 ]
 

src/pdm/__init__.py

@@ -0,0 +1,3 @@
+import pkgutil
+
+__path__ = pkgutil.extend_path(__path__, __name__)

src/pdm/__version__.py

@@ -5,7 +5,7 @@
     try:
         return importlib_metadata.version(__package__ or "pdm")
     except importlib_metadata.PackageNotFoundError:
-        return resources_read_text("pdm.models", "VERSION").strip()
+        return resources_read_text("pdm", "VERSION").strip()
 
 
 __version__ = read_version()