overhaul exception stuff

gallery_dl/exception.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright 2015-2018 Mike Fährmann
+# Copyright 2015-2019 Mike Fährmann
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 as
@@ -17,63 +17,90 @@ Exception
       |    +-- AuthorizationError
       |    +-- NotFoundError
       |    +-- HttpError
-      +-- DownloadError
-      |    +-- DownloadComplete
-      |    +-- DownloadRetry
-      +-- NoExtractorError
       +-- FormatError
+      |    +-- FilenameFormatError
+      |    +-- DirectoryFormatError
       +-- FilterError
+      +-- NoExtractorError
       +-- StopExtraction
 """
 
 
 class GalleryDLException(Exception):
     """Base class for GalleryDL exceptions"""
+    default = None
+    msgfmt = None
+    code = 1
+
+    def __init__(self, message=None):
+        if not message:
+            message = self.default
+        elif isinstance(message, Exception):
+            message = "{}: {}".format(message.__class__.__name__, message)
+        if self.msgfmt:
+            message = self.msgfmt.format(message)
+        Exception.__init__(self, message)
 
 
 class ExtractionError(GalleryDLException):
     """Base class for exceptions during information extraction"""
 
 
+class HttpError(ExtractionError):
+    """HTTP request during data extraction failed"""
+    default = "HTTP request failed"
+    code = 4
+
+
+class NotFoundError(ExtractionError):
+    """Requested resource (gallery/image) could not be found"""
+    msgfmt = "Requested {} could not be found"
+    default = "resource (gallery/image)"
+    code = 8
+
+
 class AuthenticationError(ExtractionError):
-    """Invalid or missing login information"""
+    """Invalid or missing login credentials"""
+    default = "Invalid or missing login credentials"
+    code = 16
 
 
 class AuthorizationError(ExtractionError):
     """Insufficient privileges to access a resource"""
-
-
-class NotFoundError(ExtractionError):
-    """Requested resource (gallery/image) does not exist"""
-
-
-class HttpError(ExtractionError):
-    """HTTP request during extraction failed"""
-
-
-class DownloadError(GalleryDLException):
-    """Base class for exceptions during file downloads"""
-
-
-class DownloadRetry(DownloadError):
-    """Download attempt failed and should be retried"""
-
-
-class DownloadComplete(DownloadError):
-    """Output file of attempted download is already complete"""
-
-
-class NoExtractorError(GalleryDLException):
-    """No extractor can handle the given URL"""
+    default = "Insufficient privileges to access a resource"
+    code = 16
 
 
 class FormatError(GalleryDLException):
-    """Error while building output path"""
+    """Error while building output paths"""
+    code = 32
+
+
+class FilenameFormatError(FormatError):
+    """Error while building output filenames"""
+    msgfmt = "Applying filename format string failed ({})"
+
+
+class DirectoryFormatError(FormatError):
+    """Error while building output directory paths"""
+    msgfmt = "Applying directory format string failed ({})"
 
 
 class FilterError(GalleryDLException):
     """Error while evaluating a filter expression"""
+    msgfmt = "Evaluating filter expression failed ({})"
+    code = 32
+
+
+class NoExtractorError(GalleryDLException):
+    """No extractor can handle the given URL"""
+    code = 64
 
 
 class StopExtraction(GalleryDLException):
-    """Extraction should stop"""
+    """Stop data extraction"""
+
+    def __init__(self, message=None):
+        GalleryDLException.__init__(self)
+        self.message = message
+        self.code = 1 if message else 0