1. Exceptions

TRIQS defines special exceptions, with the following characteristics :

• they derives from std::exceptions
• their method .what() returns :
  • the date and time of the exception (useful in long QMC computations…).
  • the file and line where the exception occurred
  • an additionnal error message (see example below). The error behaves like a std::stringstream, one can accumulate any message
• their method .what() returns : * a complete stack strace of the C++ code at the exception point, with demangling of the function name (on gcc and clang).

In addition, we provide a TRIQS_RUNTIME_ERROR macro to throw exception easily, Cf example below.

Note

For uniformity, it is highly recommended to use these macros when developing for TRIQS.

Example:

// automatically included in e.g. arrays, gfs, any triqs library...
#include <triqs/utility/exceptions.hpp>

int main() {
  try {
    if (2 != 3) TRIQS_RUNTIME_ERROR << " The condition is false because " << 2 << "!=" << 3;
  } catch (...) {}
}

The exception can of course be caught :

// automatically included in e.g. arrays, gfs, any triqs library...
#include <triqs/utility/exceptions.hpp>
#include <iostream>

void f() {
  try {
    if (2 != 3) TRIQS_RUNTIME_ERROR << " The condition is false because " << 2 << "!=" << 3;
  } catch (triqs::runtime_error const &e) {
    std::cout << "caught error \n" << e.what() << std::endl;
    std::cout << "C++ trace = \n" << e.trace() << std::endl;
  }
}

int main() { f(); }

caught error 
Triqs runtime error
    at /src/triqs/doc/documentation/manual/triqs/utilities/exceptions_1.cpp : 7

 The condition is false because 2!=3
Exception was thrown on node 
C++ trace =