[boost] Bad lexical_cast constructor arguments

From: Claus Tøndering (Claus.Tondering_at_[hidden])
Date: 2003-11-12 04:26:45

Under version 1.30.2 of Boost, I've noticed this problem:

In the file lexical_cast.hpp, the class lexical_cast throws this
exception:

   bad_lexical_cast(typeid(Target), typeid(Source))

But the bad_lexical_cast constructor is defined thus:

   bad_lexical_cast(
       const std::type_info &s,
       const std::type_info &t) :
       source(&s), target(&t)
   {
   }

Notice the order of the arguments!

The result is that this code:

   int i;

   try {
       int i = lexical_cast<int>("xx");
   }
   catch (bad_lexical_cast e) {
       cout << "Source type is " << e.source_type().name() << endl;
       cout << "Target type is " << e.target_type().name() << endl;
   }

produces this surprising output:

   Source type is int
   Target type is char const *

(This is compiled under MSVC. GCC produces less legible output.)

--
Claus Tondering