journal: allow JournalHandler constructor to be called with args in a positional param

This change enables to add extra fields to JournalHandler in a
configuration file loaded by `logging.config.fileConfig`, which only allows positional
parameters:

class=systemd.journal.JournalHandler
args={'level': INFO, 'SYSLOG_IDENTIFIER': 'my-cool-app'}

[zj: originally the patch added a new positional parameter to
__init__(), but that is not backwards compatible. So I added a new
classmethod to allow the positional parameters to be passed.]

1 files changed, 14 insertions, 0 deletions

diff --git a/systemd/journal.py b/systemd/journal.py
index 4168dec..64502ce 100644
--- a/systemd/journal.py
+++ b/systemd/journal.py
@@ -565,6 +565,20 @@ class JournalHandler(_logging.Handler):
         self.send = sender_function
         self._extra = kwargs
 
+    @classmethod
+    def with_args(cls, config=None):
+        """Create a JournalHandler with a configuration dictionary
+
+        This creates a JournalHandler instance, but accepts the parameters through
+        a dictionary that can be specified as a positional argument. This is useful
+        in contexts like logging.config.fileConfig, where the syntax does not allow
+        for positional arguments.
+
+        >>> JournalHandler.with_args({'SYSLOG_IDENTIFIER':'my-cool-app'})
+        <...JournalHandler ...>
+        """
+        return cls(**(config or {}))
+
     def emit(self, record):
         """Write `record` as a journal event.