Commit 51ef32bb authored by JINMEI Tatuya's avatar JINMEI Tatuya
Browse files

allow isc_throw to have a partial statement using ostream + operator<<.

added notes about design choices and possible future changes.

git-svn-id: svn:// e5f2f494-b856-4b98-b285-d166d9295462
parent 7ca848e3
......@@ -19,6 +19,7 @@
#include <stdexcept>
#include <string>
#include <sstream>
namespace isc {
......@@ -125,8 +126,30 @@ public:
/// A shortcut macro to insert known values into exception arguments.
#define isc_throw(type, args...) throw type(__FILE__, __LINE__, args)
/// It allows the \c stream argument to be part of a statement using an
/// \c ostream object and its \c operator<<. For example,
/// \code int x = 10;
/// isc_throw(SomeException, "Error happened, parameter: " << x);
/// \endcode
/// will throw an exception of class \c SomeException whose \c what string
/// will be <code>"Error happened, parameter: 10"</code>.
/// Note: the stream related operations or creation of the exception object
/// may itself throw an exception (specifically \c std::bad_alloc).
/// Even though it should be very rare, we may have to address this issue later.
/// Note: in general we hate macros and avoid using it in the code. This is
/// one of few exceptions to that policy. inline functions cannot be used
/// for embedding \c __FILE__ and \c __LINE__. This is the main reason why
/// this is defined as a macro. The convenience for the ostream is a secondary
/// purpose (if that were the only possible reason we should rather avoid
/// using a macro).
#define isc_throw(type, stream) \
do { \
std::ostringstream oss__; \
oss__ << stream; \
throw type(__FILE__, __LINE__, oss__.str().c_str()); \
} while (1)
#endif // __EXCEPTIONS_H
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