Do not use mutables as default arguments

docs/sphinxext/github.py

@@ -1,160 +1,168 b''
 """Define text roles for GitHub
 
 * ghissue - Issue
 * ghpull - Pull Request
 * ghuser - User
 
 Adapted from bitbucket example here:
 https://bitbucket.org/birkenfeld/sphinx-contrib/src/tip/bitbucket/sphinxcontrib/bitbucket.py
 
 Authors
 -------
 
 * Doug Hellmann
 * Min RK
 """
 #
 # Original Copyright (c) 2010 Doug Hellmann.  All rights reserved.
 #
 
 from docutils import nodes, utils
 from docutils.parsers.rst.roles import set_classes
 from sphinx.util.logging import getLogger
 
 info = getLogger(__name__).info
 
 def make_link_node(rawtext, app, type, slug, options):
     """Create a link to a github resource.
 
     :param rawtext: Text being replaced with link node.
     :param app: Sphinx application context
     :param type: Link type (issues, changeset, etc.)
     :param slug: ID of the thing to link to
     :param options: Options dictionary passed to role func.
     """
 
     try:
         base = app.config.github_project_url
         if not base:
             raise AttributeError
         if not base.endswith('/'):
             base += '/'
     except AttributeError as err:
         raise ValueError('github_project_url configuration value is not set (%s)' % str(err)) from err
 
     ref = base + type + '/' + slug + '/'
     set_classes(options)
     prefix = "#"
     if type == 'pull':
         prefix = "PR " + prefix
     node = nodes.reference(rawtext, prefix + utils.unescape(slug), refuri=ref,
                            **options)
     return node
 
-def ghissue_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
+def ghissue_role(name, rawtext, text, lineno, inliner, options=None, content=None):
     """Link to a GitHub issue.
 
     Returns 2 part tuple containing list of nodes to insert into the
     document and a list of system messages.  Both are allowed to be
     empty.
 
     :param name: The role name used in the document.
     :param rawtext: The entire markup snippet, with role.
     :param text: The text marked with the role.
     :param lineno: The line number where rawtext appears in the input.
     :param inliner: The inliner instance that called us.
     :param options: Directive options for customization.
     :param content: The directive content for customization.
     """
+    if options is None:
+        options = {}
 
     try:
         issue_num = int(text)
         if issue_num <= 0:
             raise ValueError
     except ValueError:
         msg = inliner.reporter.error(
             'GitHub issue number must be a number greater than or equal to 1; '
             '"%s" is invalid.' % text, line=lineno)
         prb = inliner.problematic(rawtext, rawtext, msg)
         return [prb], [msg]
     app = inliner.document.settings.env.app
     #info('issue %r' % text)
     if 'pull' in name.lower():
         category = 'pull'
     elif 'issue' in name.lower():
         category = 'issues'
     else:
         msg = inliner.reporter.error(
             'GitHub roles include "ghpull" and "ghissue", '
             '"%s" is invalid.' % name, line=lineno)
         prb = inliner.problematic(rawtext, rawtext, msg)
         return [prb], [msg]
     node = make_link_node(rawtext, app, category, str(issue_num), options)
     return [node], []
 
-def ghuser_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
+def ghuser_role(name, rawtext, text, lineno, inliner, options=None, content=None):
     """Link to a GitHub user.
 
     Returns 2 part tuple containing list of nodes to insert into the
     document and a list of system messages.  Both are allowed to be
     empty.
 
     :param name: The role name used in the document.
     :param rawtext: The entire markup snippet, with role.
     :param text: The text marked with the role.
     :param lineno: The line number where rawtext appears in the input.
     :param inliner: The inliner instance that called us.
     :param options: Directive options for customization.
     :param content: The directive content for customization.
     """
+    if options is None:
+        options = {}
+
     app = inliner.document.settings.env.app
     #info('user link %r' % text)
     ref = 'https://www.github.com/' + text
     node = nodes.reference(rawtext, text, refuri=ref, **options)
     return [node], []
 
-def ghcommit_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
+def ghcommit_role(name, rawtext, text, lineno, inliner, options=None, content=None):
     """Link to a GitHub commit.
 
     Returns 2 part tuple containing list of nodes to insert into the
     document and a list of system messages.  Both are allowed to be
     empty.
 
     :param name: The role name used in the document.
     :param rawtext: The entire markup snippet, with role.
     :param text: The text marked with the role.
     :param lineno: The line number where rawtext appears in the input.
     :param inliner: The inliner instance that called us.
     :param options: Directive options for customization.
     :param content: The directive content for customization.
     """
+    if options is None:
+        options = {}
+
     app = inliner.document.settings.env.app
     #info('user link %r' % text)
     try:
         base = app.config.github_project_url
         if not base:
             raise AttributeError
         if not base.endswith('/'):
             base += '/'
     except AttributeError as err:
         raise ValueError('github_project_url configuration value is not set (%s)' % str(err)) from err
 
     ref = base + text
     node = nodes.reference(rawtext, text[:6], refuri=ref, **options)
     return [node], []
 
 
 def setup(app):
     """Install the plugin.
 
     :param app: Sphinx application context.
     """
     info('Initializing GitHub plugin')
     app.add_role('ghissue', ghissue_role)
     app.add_role('ghpull', ghissue_role)
     app.add_role('ghuser', ghuser_role)
     app.add_role('ghcommit', ghcommit_role)
     app.add_config_value('github_project_url', None, 'env')
 
     metadata = {'parallel_read_safe': True, 'parallel_write_safe': True}
     return metadata