1 files changed, 84 insertions, 0 deletions
diff --git a/pomu/source/base.py b/pomu/source/base.py
new file mode 100644
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+++ b/pomu/source/base.py
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+"""
+A base package source module.
+A package source module shall provide two classes: a class representing
+a package (implementation details of the source, package-specific metadata,
+fetching logic etc.), and the source per se: it is responsible for parsing
+package specifications and fetching the specified package, as well as
+instantiating specific packages from the metadata directory.
+"""
+
+from pomu.source import dispatcher
+
+class PackageBase():
+    """
+    This is a base class for storing package-specific metadata.
+    It shall be subclassed explicitely.
+    The class is responsible for fetching the package, and reading/writing
+    the package-specific metadata.
+    """
+
+    """The implementation shall provide a name for the package type"""
+    __name__ = None
+
+    def fetch(self):
+        """
+        A method which is responsible for fetching the package: it should return a Package object (specifying set of files with sufficient metadata), and specify this package object as the backend for the Package object (to store source-specific metadata).
+        """
+        raise NotImplementedError()
+
+    @staticmethod
+    def from_data_dir(pkgdir):
+        """
+        This method is responsible for instantiating source-specific metadata
+        from the metadata directory.
+        It shall return an instance of this class, and take a path to the meta
+        directory.
+        """
+        raise NotImplementedError()
+
+    def write_meta(self, pkgdir):
+        """
+        This method shall write source-specific metadata to the provided
+        metadata directory.
+        """
+        raise NotImplementedError()
+
+    def __str__(self):
+        """
+        The implementation shall provide a method to pretty-print
+        package-specific metadata (displayed in show command).
+        Example:
+        return '{}/{}-{} (from {})'.format(self.category, self.name, self.version, self.path)
+        """
+        raise NotImplementedError()
+
+@dispatcher.source
+class BaseSource:
+    """
+    This is the base package source class.
+    It should be decorated with @dispatcher.source.
+    The implementation shall provide methods to parse the package specification,
+    which would be called by the dispatcher (see manager.py for details).
+    Parser methods shall be decorated with @dispatcher.handler(priority=...)
+    decorator (default is 5).
+    It shall provide a method to instantiate a package of this type from the
+    metadata directory.
+    """
+    @dispatcher.handler()
+    def parse_full(uri):
+        """
+        This method shall parse a full package specification (which starts with
+        the backend name, followed by a colon).
+        It shall return a package, wrapped in Result.
+        """
+        raise NotImplementedError()
+
+    @classmethod
+    def from_meta_dir(cls, metadir):
+        """
+        This method is responsible for instantiating package-specific metadata
+        from the metadata directory.
+        Example:
+        return PackageBase.from_data_dir(metadir)
+        """
+        raise NotImplementedError()