pexConfig.py

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# This file is part of daf_butler.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (http://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
from __future__ import annotations
 
__all__ = ("PexConfigFormatter", )
 
import os.path
 
from typing import (
    Any,
    Optional,
    Type,
)
 
from lsst.pex.config import Config
from lsst.daf.butler.formatters.file import FileFormatter
 
 
class PexConfigFormatter(FileFormatter):
    """Interface for reading and writing pex.config.Config objects from disk.
    """
    extension = ".py"
 
    def _readFile(self, path: str, pytype: Optional[Type[Any]] = None) -> Any:
        """Read a pex.config.Config instance from the given file.
 
        Parameters
        ----------
        path : `str`
            Path to use to open the file.
        pytype : `type`, optional
            Class to use to read the config file.
 
        Returns
        -------
        data : `lsst.pex.config.Config`
            Instance of class ``pytype`` read from config file. `None`
            if the file could not be opened.
        """
        if not os.path.exists(path):
            return None
 
        # Automatically determine the Config class from the serialized form
        with open(path, "r") as fd:
            config_py = fd.read()
        return Config._fromPython(config_py)
 
    def _writeFile(self, inMemoryDataset: Any) -> None:
        """Write the in memory dataset to file on disk.
 
        Parameters
        ----------
        inMemoryDataset : `object`
            Object to serialize.
 
        Raises
        ------
        Exception
            The file could not be written.
        """
        inMemoryDataset.save(self.fileDescriptor.location.path)