.. highlight:: python

.. _Debug: 

Bound checking and debug macros
===================================

To be fast, by default, no check are made on the indices while accessing elements or slicing.
However, checks can be activated in two ways: 

* Adding the `BOUND_CHECK` option 

* Defining the debug macro TRIQS_ARRAYS_ENFORCE_BOUNDCHECK, which switches the default option to `BOUND_CHECK`
  for all arrays, matrices and vectors.

In both cases, if the indices are not within the domain of defintion, an exception triqs::arrays::key_error 
will be thrown. It's .what() returns the file and line where the exception occurs, with the stack of all in C++, 
e.g. :

.. literalinclude:: ./debug_0.cpp

.. note:: Bound Checking is not necessarly used for debugging. You may used it for a given array, catching exception.
   Beware however that bound checking comes with some performance penalty.