...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
#include <boost/multiprecision/debug_adaptor.hpp>
namespace boost{ namespace multiprecision{ template <Backend> class debug_adaptor; template <class Number> using debug_adaptor_t = number<debug_adaptor<typename Number::backend_type>, Number::et> }} // namespaces
The debug_adaptor
type
is used in conjunction with number
and some other backend type: it acts as a thin wrapper around some other
backend to class number
and intercepts all operations on that object storing the result as a string
within itself.
This type provides numeric_limits
support whenever the template argument Backend does so.
This type is particularly useful when your debugger provides a good view
of std::string
: when this is the case multiprecision
values can easily be inspected in the debugger by looking at the debug_value
member of debug_adaptor
.
The down side of this approach is that runtimes are much slower when using
this type. Set against that it can make debugging very much easier, certainly
much easier than sprinkling code with printf
statements.
When used in conjunction with the Visual C++ debugger visualisers, the
value of a multiprecision type that uses this backend is displayed in the
debugger just a fundamental
(built-in) value would be, here we're inspecting a value of type
number<debug_adaptor<cpp_dec_float<50> >
>
:
Otherwise you will need to expand out the view and look at the "debug_value" member:
It works for all the backend types equally too, here it is inspecting a
number<debug_adaptor<gmp_rational>
>
:
The template alias debug_adaptor_t
is used as a shortcut for converting some other number type to it's debugged
equivalent, for example:
using mpfr_float_debug = debug_adaptor_t<mpfr_float>;
Defines mpfr_float_debug
to be the debugged equivalent of mpfr_float
.