python: default op_keylist_start parameters.

* lang/python/gpgme.i: Added gpgme_op_keylist_start with defaults
* lang/python/tests/t-keylist.py: Added tests for default parameters
--

To increase the ease of use, op_keylist_start
parameters default to sensible values.
The empty string matches all keys.
We assume that the user wants to retrieve public keys most of the time,
so we default to public keys rather than secret keys.

Signed-off-by: Tobias Mueller <muelli@cryptobitch.de>

lang/python/gpgme.i

@@ -541,6 +541,15 @@ wrapresult(gpgme_vfs_mount_result_t, "VFSMountResult")
     }
 }
 
+
+/* With SWIG, you can define default arguments for parameters.
+ * While it's legal in C++ it is not in C, so we cannot change the
+ * already existing gpgme.h. We need, however, to declare the function
+ * *before* SWIG loads it from gpgme.h. Hence, we define it here.     */
+gpgme_error_t gpgme_op_keylist_start (gpgme_ctx_t ctx,
+                      const char *pattern="",
+                      int secret_only=0);
+
 /* Include the unmodified <gpgme.h> for cc, and the cleaned-up local
    version for SWIG.  We do, however, want to hide certain fields on
    some structs, which we provide prior to including the version for

lang/python/tests/t-keylist.py

@@ -219,6 +219,18 @@ result = c.op_keylist_result()
 assert not result.truncated, "Key listing unexpectedly truncated"
 
 
+# We test for a parameter-less keylist
+keyring_length = len(list(c.op_keylist_all()))
+assert keyring_length > 1,\
+                "Expected to find some keys, but got %r" % keyring_length
+
+# Then we do want to call with a pattern, only
+# i.e. without giving secret=0
+alpha_keys = list(c.op_keylist_all(b"Alpha"))
+assert len(alpha_keys) == 1, "Expected only one key for 'Alpha', got %r" % len(alpha_keys)
+
+
+
 for i, key in enumerate(c.keylist()):
     try:
         if len(keys[i]) == 4: