Re: [Boost-users] [multi_index] passing 'cons t TYPE' as 'this' argument discards qualifiers

28 Dec 2007

      hi joaquín,

now it works. thank you.
...
...
are there possibilities to avoid the 'std::string' for the 'name' 
key?
I'm not getting this question. Could you please elaborate?
i would like to know if it is possible to use char[] or char* as an alphanumeric key value and not std::string.
improper tests didn't work.

daniel
...
----- Mensaje original -----
De: damny@web.de
Fecha: Martes, Diciembre 25, 2007 5:17 pm
Asunto: [Boost-users] [multi_index] passing 'cons t TYPE' as 'this' 
argument discards qualifiers
Para: boost-users@lists.boost.org
...
merry xmas everyone,
Merry Xmas :)
[...]
...
class cClass {
 private:
   int att1;
 public:
   std::string  nme;  // name
   int               idf;    // identifier
   cClass();
   cClass(std::string nme, int idf);
   int get_attribute();
};
[...]
...
mMapByNme::iterator itrNme = locMsg.get<0>().find("name1");
 mMapByIdf::iterator itrIdf = locMsg.get<1>().find(456);
 printf( "att1 = %d\n", itrNme->get_attribute() );
[...]
main.cpp: In function `int main()':
main.cpp:33: error: passing 'const cClass' as 'this' argument of 
'int cClass::get_attribute()' discards qualifiers
Process terminated with status 1 (0 minutes, 20 seconds)
any hints how to solve the problem?
The problem here is that elements of a multi_index_container
are immutable, and the iterators ony grant const access
to them. In this regard, the behavior is the same as that
of a regular std::set. To solve your particular problem you can
const-qualify the offending member function:
int get_attribute() const;
...
how to encapsulate this special multi_index into a class, that 
fits the above description of the needed 'map'.
You should probably consider whether Boost.Bimap could
be a better approach, but I see you're already discussing
this issue with Matías.
...
are there possibilities to avoid the 'std::string' for the 'name' 
key?
I'm not getting this question. Could you please elaborate?
...
where are the more easier examples for C++-templates/boost
newbies like me :o) ?
HTH,
Joaquín M López Muñoz
Telefónica, Investiación y Desarrollo
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Re: [Boost-users] [multi_index] passing 'cons t TYPE' as 'this' argument discards qualifiers

damny＠web.de