Introduce gdbpy_enter_varobj and use it

This introduces gdbpy_enter_varobj, a subclass of gdbpy_enter; then
changes one function in py-varobj.c to use it.  gdbpy_enter_varobj
takes a varobj as an argument, similar to varobj_ensure_python_env.

2017-01-10  Tom Tromey  <tom@tromey.com>

	* varobj.c (gdbpy_enter_varobj): New constructor.
	* python/python-internal.h (gdbpy_enter_varobj): New class.
	* python/py-varobj.c (py_varobj_get_iterator): Use
	gdbpy_enter_varobj.

1 files changed, 12 insertions, 0 deletions

diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index a3b9b74..41275bb 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -526,6 +526,18 @@ class gdbpy_enter
   PyObject *m_error_type, *m_error_value, *m_error_traceback;
 };
 
+/* Like gdbpy_enter, but takes a varobj.  This is a subclass just to
+   make constructor delegation a little nicer.  */
+class gdbpy_enter_varobj : public gdbpy_enter
+{
+ public:
+
+  /* This is defined in varobj.c, where it can access varobj
+     internals.  */
+  gdbpy_enter_varobj (const struct varobj *var);
+
+};
+
 struct cleanup *ensure_python_env (struct gdbarch *gdbarch,
 				   const struct language_defn *language);