Add simple, explicit CLI to install a .whl file

src/installer/__main__.py

@@ -0,0 +1,67 @@
+"""CLI - run as python -m installer."""
+import argparse
+
+from . import install
+from .destinations import SchemeDictionaryDestination
+from .sources import WheelFile
+
+
+def main():
+    """Entry point for CLI."""
+    ap = argparse.ArgumentParser("python -m installer")
+    ap.add_argument("wheel_file", help="Path to a .whl file to install")
+
+    ap.add_argument(
+        "--interpreter", required=True, help="Interpreter path to be used in scripts"
+    )
+    ap.add_argument(
+        "--script-kind",
+        required=True,
+        choices=["posix", "win-ia32", "win-amd64", "win-arm", "win-arm64"],
+        help="Kind of launcher to create for each script",
+    )
+
+    dest_args = ap.add_argument_group("Destination directories")
+    dest_args.add_argument(
+        "--purelib",
+        required=True,
+        help="Directory for platform-independent Python modules",
+    )
+    dest_args.add_argument(
+        "--platlib",
+        required=True,
+        help="Directory for platform-dependent Python modules",
+    )
+    dest_args.add_argument(
+        "--headers", required=True, help="Directory for C header files"
+    )
+    dest_args.add_argument(
+        "--scripts", required=True, help="Directory for executable scripts"
+    )
+    dest_args.add_argument(
+        "--data", required=True, help="Directory for external data files"
+    )
+    args = ap.parse_args()
+
+    destination = SchemeDictionaryDestination(
+        {
+            "purelib": args.purelib,
+            "platlib": args.platlib,
+            "headers": args.headers,
+            "scripts": args.scripts,
+            "data": args.data,
+        },
+        interpreter=args.interpreter,
+        script_kind=args.script_kind,
+    )
+
+    with WheelFile.open(args.wheel_file) as source:
+        install(
+            source=source,
+            destination=destination,
+            additional_metadata={},
+        )
+
+
+if __name__ == "__main__":
+    main()