Re: C++ exception error messages
James K. Lowden wrote:
Volker Lukas wrote:
Nothing, except that the exception object could contain a buffer
declared "mutable", and could try to generate a elaborate message,
Why mutable? std::string::c_str() is const.
std::exception::what() is const.
class X : public std::exception {
[...]
virtual char const* what() throw() {
try {
s = "...";
return s.c_str();
} catch(...) {
That assignment mystifies me. You elided anything that could be
assigned to s. It seems likely to me that the constructor for X
would initialize s.
The idea is to not build the message at the throw site, because we
could be low on resources. At the catch site, after some stack
unwinding, this could have improved.
It also avoids building the message if what() is never called.
Bo Persson
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