python: Implement the context manager protocol.

* lang/python/pyme/core.py (Context.__del__): Make function
idemptotent.
(Context.{__enter__,__exit__}): Implement the context manager
protocol.
(Data.__del__): Make function idemptotent, drop debug print.
(Data.{__enter__,__exit__}): Implement the context manager
protocol.
* lang/python/tests/t-idiomatic.py: Demonstrate this.

Signed-off-by: Justus Winter <[email protected]>

1 files changed, 15 insertions, 2 deletions

diff --git a/lang/python/pyme/core.py b/lang/python/pyme/core.py
index 71c6828a..4b3e08a4 100644
--- a/lang/python/pyme/core.py
+++ b/lang/python/pyme/core.py
@@ -147,8 +147,15 @@ class Context(GpgmeWrapper):
         self._free_passcb()
         self._free_progresscb()
         self._free_statuscb()
-        if self.own and pygpgme.gpgme_release:
+        if self.own and self.wrapped and pygpgme.gpgme_release:
             pygpgme.gpgme_release(self.wrapped)
+            self.wrapped = None
+
+    # Implement the context manager protocol.
+    def __enter__(self):
+        return self
+    def __exit__(self, type, value, tb):
+        self.__del__()
 
     def _free_passcb(self):
         if self.last_passcb != None:
@@ -420,10 +427,16 @@ class Data(GpgmeWrapper):
         if self.wrapped != None and pygpgme.gpgme_data_release:
             pygpgme.gpgme_data_release(self.wrapped)
             if self._callback_excinfo:
-                print(self._callback_excinfo)
                 pygpgme.pygpgme_raise_callback_exception(self)
+            self.wrapped = None
         self._free_datacbs()
 
+    # Implement the context manager protocol.
+    def __enter__(self):
+        return self
+    def __exit__(self, type, value, tb):
+        self.__del__()
+
     def _free_datacbs(self):
         if self.data_cbs != None:
             if pygpgme.pygpgme_clear_generic_cb: