Move package management code out of subproc.py

package_manager/bpkg/utils.py

@@ -0,0 +1,48 @@
+
+class InplaceBackup:
+    """Utility class for moving a file out of the way by appending a '~'"""
+
+    log = logging.getLogger('%s.inplace-backup' % __name__)
+
+    def __init__(self, path: pathlib.Path):
+        self.path = path
+        self.backup()
+
+    def backup(self):
+        """Move 'path' to 'path~'"""
+        if not self.path.exists():
+            raise FileNotFoundError("Can't backup path which doesn't exist")
+
+        self.backup_path = pathlib.Path(str(self.path) + '~')
+        if self.backup_path.exists():
+            self.log.warning("Overwriting existing backup '{}'".format(self.backup_path))
+            self._rm(self.backup_path)
+
+        shutil.move(str(self.path), str(self.backup_path))
+
+    def restore(self):
+        """Move 'path~' to 'path'"""
+        try:
+            getattr(self, 'backup_path')
+        except AttributeError as err:
+            raise RuntimeError("Can't restore file before backing it up") from err
+
+        if not self.backup_path.exists():
+            raise FileNotFoundError("Can't restore backup which doesn't exist")
+
+        if self.path.exists():
+            self.log.warning("Overwriting '{0}' with backup file".format(self.path))
+            self._rm(self.path)
+
+        shutil.move(str(self.backup_path), str(self.path))
+
+    def remove(self):
+        """Remove 'path~'"""
+        self._rm(self.backup_path)
+
+    def _rm(self, path: pathlib.Path):
+        """Just delete whatever is specified by `path`"""
+        if path.is_dir():
+            shutil.rmtree(str(path))
+        else:
+            path.unlink()