[lmi-commits] [5981] Add a GUI-testing exception class

[Greg Chicares]

Revision: 5981
          http://svn.sv.gnu.org/viewvc/?view=rev&root=lmi&revision=5981
Author:   chicares
Date:     2014-10-11 12:34:33 +0000 (Sat, 11 Oct 2014)
Log Message:
-----------
Add a GUI-testing exception class

Modified Paths:
--------------
    lmi/trunk/ChangeLog
    lmi/trunk/handle_exceptions.hpp

Modified: lmi/trunk/ChangeLog
===================================================================
--- lmi/trunk/ChangeLog 2014-10-10 17:22:39 UTC (rev 5980)
+++ lmi/trunk/ChangeLog 2014-10-11 12:34:33 UTC (rev 5981)
@@ -34299,3 +34299,9 @@
   assert_lmi_test.cpp
 Resolve failure noted 20141010T1713Z.
 
+20141011T1234Z <address@hidden> [533]
+
+  handle_exceptions.hpp
+Add a GUI-testing exception class. See:
+  http://lists.nongnu.org/archive/html/lmi/2014-10/msg00036.html
+

Modified: lmi/trunk/handle_exceptions.hpp
===================================================================
--- lmi/trunk/handle_exceptions.hpp     2014-10-10 17:22:39 UTC (rev 5980)
+++ lmi/trunk/handle_exceptions.hpp     2014-10-11 12:34:33 UTC (rev 5981)
@@ -30,6 +30,7 @@
 
 #include <cstdlib>   // std::exit()
 #include <exception>
+#include <string>
 
 /// This function, of type std::terminate_handler, is intended to be
 /// used as the argument of std::set_terminate().
@@ -42,6 +43,29 @@
     std::exit(EXIT_FAILURE);
 }
 
+/// An extraordinary exception used only for testing the GUI.
+///
+/// The production system (distributed to end users) is tested by
+/// running its code under the supervision of the 'wx_test' program
+/// (which is for developer use only)--in which case 'wx_test'
+/// invokes the production code (replacing only its main() function)
+/// and tests simulated GUI events. For this sole, exclusive purpose,
+/// wx_test_exception is needed--and must pass through the production
+/// code's exception traps as a neutrino through a fishing net. In any
+/// other situation, it undermines the
+///   catch(...) {report_exception();}
+/// idiom, potentially causing great harm; to forestall that, a ctor
+/// is declared here, but implemented only in the 'wx_test' code.
+///
+/// Implicitly-declared special member functions do the right thing.
+
+class wx_test_exception
+  :public std::exception
+{
+  public:
+    explicit wx_test_exception(std::string const& what_arg);
+};
+
 /// Handle an uncaught exception, showing a description if available
 /// readily through what(), with the following idiomatic usage:
 ///   catch(...) {report_exception();}
@@ -55,12 +79,15 @@
 ///   "Before the try-block in report_exception, query
 ///   std::uncaught_exception() to determine if an exception is
 ///   active. If it is not, throw std::logic_error or some exception
-//    that you know that your framework will catch."
+///   that you know that your framework will catch."
 /// but actually that's invalid--see:
 ///   
http://groups.google.com/group/comp.lang.c++.moderated/msg/aa7ce713ee90c044
 ///   "The only problem with uncaught_exception is that it doesn't
 ///   tell you when you're in a catch(...) { ... throw; } block"
 ///
+/// Simply rethrow when wx_test_exception is caught: see the comments
+/// accompanying its declaration.
+///
 /// Show no message when hobsons_choice_exception is caught. It's
 /// thrown only when
 ///  - an appropriate message was just shown, and then
@@ -68,11 +95,11 @@
 /// in which case it's pointless to repeat the same message.
 ///
 /// See
-//   http://article.gmane.org/gmane.comp.gnu.mingw.user/18355
-//     [2005-12-16T09:20:33Z from Greg Chicares]
+///  http://article.gmane.org/gmane.comp.gnu.mingw.user/18355
+///    [2005-12-16T09:20:33Z from Greg Chicares]
 /// for a grave gcc problem with msw dlls, which is fixed
-//   http://article.gmane.org/gmane.comp.gnu.mingw.user/18594
-//     [2006-01-10T22:00:24Z from Danny Smith]
+///  http://article.gmane.org/gmane.comp.gnu.mingw.user/18594
+///    [2006-01-10T22:00:24Z from Danny Smith]
 /// in MinGW gcc-3.4.5; it is avoided altogether by writing this
 /// function inline, so this code works with earlier versions, too.
 
@@ -82,6 +109,10 @@
         {
         throw;
         }
+    catch(wx_test_exception const&)
+        {
+        throw;
+        }
     catch(hobsons_choice_exception const&)
         {
         }