DM-26683: Make exporting dimension data friendlier

python/lsst/daf/butler/__init__.py

@@ -11,4 +11,5 @@
 from ._butlerConfig import *
 from ._deferredDatasetHandle import *
 from ._butler import *
+from .transfers import YamlRepoExportBackend, YamlRepoImportBackend
 from .version import *

python/lsst/daf/butler/_butler.py

@@ -62,7 +62,6 @@
     DatasetType,
     Datastore,
     FileDataset,
-    RepoExport,
     StorageClassFactory,
     ValidationError,
 )
@@ -72,6 +71,7 @@
 from ._butlerConfig import ButlerConfig
 from .registry import Registry, RegistryConfig, CollectionType
 from .registry.wildcards import CollectionSearch
+from .transfers import RepoExportContext
 
 log = logging.getLogger(__name__)
 
@@ -1205,12 +1205,12 @@ def ingest(self, *datasets: FileDataset, transfer: Optional[str] = "auto", run:
     def export(self, *, directory: Optional[str] = None,
                filename: Optional[str] = None,
                format: Optional[str] = None,
-               transfer: Optional[str] = None) -> ContextManager[RepoExport]:
+               transfer: Optional[str] = None) -> ContextManager[RepoExportContext]:
         """Export datasets from the repository represented by this `Butler`.
 
         This method is a context manager that returns a helper object
-        (`RepoExport`) that is used to indicate what information from the
-        repository should be exported.
+        (`RepoExportContext`) that is used to indicate what information from
+        the repository should be exported.
 
         Parameters
         ----------
@@ -1266,8 +1266,8 @@ def export(self, *, directory: Optional[str] = None,
         with open(filename, 'w') as stream:
             backend = BackendClass(stream)
             try:
-                helper = RepoExport(self.registry, self.datastore, backend=backend,
-                                    directory=directory, transfer=transfer)
+                helper = RepoExportContext(self.registry, self.datastore, backend=backend,
+                                           directory=directory, transfer=transfer)
                 yield helper
             except BaseException:
                 raise

python/lsst/daf/butler/_butlerConfig.py

@@ -37,10 +37,10 @@
     Config,
     DatastoreConfig,
     DimensionConfig,
-    RepoTransferFormatConfig,
     StorageClassConfig,
 )
 from .registry import RegistryConfig
+from .transfers import RepoTransferFormatConfig
 
 CONFIG_COMPONENT_CLASSES = (RegistryConfig, StorageClassConfig,
                             DatastoreConfig, DimensionConfig,

python/lsst/daf/butler/core/__init__.py

@@ -25,6 +25,6 @@
 from .storageClassDelegate import *
 from .storedFileInfo import *
 from .dimensions import *
-from .repoTransfers import *
+from .fileDataset import *
 from . import time_utils
 from .timespan import *

python/lsst/daf/butler/core/datastore.py

@@ -55,12 +55,12 @@
 from .exceptions import ValidationError, DatasetTypeNotSupportedError
 from .constraints import Constraints
 from .storageClass import StorageClassFactory
+from .fileDataset import FileDataset
 
 if TYPE_CHECKING:
     from ..registry.interfaces import DatastoreRegistryBridgeManager
     from .datasets import DatasetRef, DatasetType
     from .configSupport import LookupKey
-    from .repoTransfers import FileDataset
     from .storageClass import StorageClass
     from ._butlerUri import ButlerURI
 

python/lsst/daf/butler/core/dimensions/universe.py

@@ -158,7 +158,7 @@ def __new__(cls, config: Optional[Config] = None) -> DimensionUniverse:
         return self
 
     def __repr__(self) -> str:
-        return f"DimensionUniverse({self})"
+        return f"DimensionUniverse({self._version})"
 
     def __getitem__(self, name: str) -> DimensionElement:
         return self._elements[name]

python/lsst/daf/butler/core/fileDataset.py

@@ -0,0 +1,68 @@
+# 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__ = ["FileDataset"]
+
+from dataclasses import dataclass
+from typing import (
+    List,
+    Optional,
+    Union,
+)
+
+
+from .datasets import DatasetRef
+from .formatter import FormatterParameter
+
+
+@dataclass
+class FileDataset:
+    """A struct that represents a dataset exported to a file.
+    """
+    __slots__ = ("refs", "path", "formatter")
+
+    refs: List[DatasetRef]
+    """Registry information about the dataset. (`list` of `DatasetRef`).
+    """
+
+    path: str
+    """Path to the dataset (`str`).
+
+    If the dataset was exported with ``transfer=None`` (i.e. in-place),
+    this is relative to the datastore root (only datastores that have a
+    well-defined root in the local filesystem can be expected to support
+    in-place exports).  Otherwise this is relative to the directory passed
+    to `Datastore.export`.
+    """
+
+    formatter: Optional[FormatterParameter]
+    """A `Formatter` class or fully-qualified name.
+    """
+
+    def __init__(self, path: str, refs: Union[DatasetRef, List[DatasetRef]], *,
+                 formatter: Optional[FormatterParameter] = None):
+        self.path = path
+        if isinstance(refs, DatasetRef):
+            refs = [refs]
+        self.refs = refs
+        self.formatter = formatter