# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1554818639 -7200
# Node ID e133bda9c11835ab7205df6e2a14a355863722d5
# Parent  37470621404825f47b84e616be7b5e83cb646a78
Introduced a general processing error that can be handled in moinconvert. This
permits more graceful handling of Graphviz errors.

diff -r 374706214048 -r e133bda9c118 moinconvert
--- a/moinconvert	Fri Mar 15 18:37:04 2019 +0100
+++ b/moinconvert	Tue Apr 09 16:03:59 2019 +0200
@@ -19,7 +19,8 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-from moinformat import make_parser, make_serialiser, Metadata, parse, serialise
+from moinformat import errors, make_parser, make_serialiser, Metadata, parse, \
+                       serialise
 from os.path import split
 import sys
 
@@ -379,6 +380,9 @@
 """
 
 if __name__ == "__main__":
-    main()
+    try:
+        main()
+    except errors.ProcessingError, exc:
+        print str(exc)
 
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r 374706214048 -r e133bda9c118 moinformat/__init__.py
--- a/moinformat/__init__.py	Fri Mar 15 18:37:04 2019 +0100
+++ b/moinformat/__init__.py	Tue Apr 09 16:03:59 2019 +0200
@@ -3,7 +3,7 @@
 """
 Moin wiki format tools.
 
-Copyright (C) 2017, 2018 Paul Boddie <paul@boddie.org.uk>
+Copyright (C) 2017, 2018, 2019 Paul Boddie <paul@boddie.org.uk>
 
 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
@@ -26,5 +26,6 @@
 from moinformat.parsers import get_parser, make_parser, parse
 from moinformat.serialisers import get_serialiser, make_serialiser, serialise
 from moinformat.themes import make_theme
+import moinformat.errors as errors
 
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r 374706214048 -r e133bda9c118 moinformat/errors.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/moinformat/errors.py	Tue Apr 09 16:03:59 2019 +0200
@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+
+"""
+Moin wiki processing errors.
+
+Copyright (C) 2019 Paul Boddie <paul@boddie.org.uk>
+
+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/>.
+"""
+
+class ProcessingError(Exception):
+
+    "A generic processing error."
+
+    def __init__(self, errors):
+        self.errors = errors
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__class__.__name__, self.errors)
+
+    def __str__(self):
+        return "Error: %s\nMessage: %s\n" % (self.__class__.__name__, self.errors)
+
+# vim: tabstop=4 expandtab shiftwidth=4
diff -r 374706214048 -r e133bda9c118 moinformat/serialisers/html/graphviz.py
--- a/moinformat/serialisers/html/graphviz.py	Fri Mar 15 18:37:04 2019 +0100
+++ b/moinformat/serialisers/html/graphviz.py	Tue Apr 09 16:03:59 2019 +0200
@@ -20,7 +20,7 @@
 """
 
 from moinformat.serialisers.common import Serialiser, escape_attr, escape_text
-from moinformat.utils.graphviz import Graphviz, GraphvizError, IMAGE_FORMATS, \
+from moinformat.utils.graphviz import Graphviz, IMAGE_FORMATS, \
                                       get_output_identifier
 
 # Utility functions.
diff -r 374706214048 -r e133bda9c118 moinformat/utils/graphviz.py
--- a/moinformat/utils/graphviz.py	Fri Mar 15 18:37:04 2019 +0100
+++ b/moinformat/utils/graphviz.py	Tue Apr 09 16:03:59 2019 +0200
@@ -3,7 +3,7 @@
 """
 Graphviz utilities.
 
-Copyright (C) 2018 Paul Boddie <paul@boddie.org.uk>
+Copyright (C) 2018, 2019 Paul Boddie <paul@boddie.org.uk>
 
 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
@@ -19,6 +19,7 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
+from moinformat.errors import ProcessingError
 from os.path import exists, join
 from StringIO import StringIO
 from subprocess import Popen, PIPE
@@ -184,12 +185,11 @@
 
 # Classes for interacting with Graphviz.
 
-class GraphvizError(Exception):
+class GraphvizError(ProcessingError):
 
     "An error produced when using Graphviz."
 
-    def __init__(self, errors):
-        self.errors = errors
+    pass
 
 class Graphviz: