Add a metadata version field

codearchiver/core.py

@@ -88,6 +88,7 @@ class Metadata(list[tuple[str, str]]):
 	fields: tuple[MetadataField] = (
 		MetadataField('codearchiver version', required = True, repeatable = False),
 		MetadataField('Module', required = True, repeatable = False),
+		MetadataField('Metadata version', required = True, repeatable = False),
 		MetadataField('ID', required = True, repeatable = False),
 		MetadataField('Input URL', required = True, repeatable = False),
 		MetadataField('Filename', required = True, repeatable = False),
@@ -96,6 +97,9 @@ class Metadata(list[tuple[str, str]]):
 	)
 	'''The fields for this metadata collection'''
 
+	version: int = 0
+	'''Version, incremented on every backward-incompatible change'''
+
 	_allFieldsCache: typing.Optional[tuple[MetadataField]] = None
 
 	def append(self, *args):
@@ -394,6 +398,13 @@ class Module(metaclass = ModuleMeta):
 		idx = type(self).MetadataClass()
 		idx.append('codearchiver version', codearchiver.version.__version__)
 		idx.append('Module', type(self).name)
+		metadataVersions = []
+		for cls in reversed(type(self).MetadataClass.mro()):
+			version = cls.__dict__.get('version')
+			if version is None:
+				continue
+			metadataVersions.append(f'{cls.__module__}.{cls.__qualname__}/{version}')
+		idx.append('Metadata version', ' '.join(metadataVersions))
 		idx.append('ID', self._id)
 		idx.append('Input URL', self._url)
 		idx.append('Filename', filename)

codearchiver/modules/git.py

@@ -20,6 +20,7 @@ class GitMetadata(codearchiver.core.Metadata):
 		codearchiver.core.MetadataField(key = 'Root commit', required = True, repeatable = True),
 		codearchiver.core.MetadataField(key = 'Commit', required = False, repeatable = True),
 	)
+	version = 0
 
 
 class Git(codearchiver.core.Module):