e3299e98   
   From: 0xCDCDCDCD@gmx.at   
      
   On 26.09.2011 20:27, Thiago Adams wrote:   
   > I was playing with a string class which I want to represent   
   > an immutable string object.   
   >   
   > class string {   
   >    const char* const m_psz;   
   > public:   
   >    string(const char* psz) : m_psz(_strdup(psz)) {}   
   >    ~string() { free((void*)m_psz); }   
   >    //..only const methods...   
   > };   
   >   
   > When I wrote the move constructor the compiler complained   
   > about the const data member (m_psz).   
   >   
   > string(string&&  s) : m_psz(s.m_psz)   
   > {   
   >      s.m_psz = nullptr; //error l-value specifies const object   
   > }   
   >   
   > Then I realized that is not be possible to move from const data   
   > members.   
   >   
   > What would you do in this case?   
   >   
   > 1) Do not use move constructor?   
   > 2) Remove the const data member keeping the const member functions?   
   > 3) ?   
   >   
   >   
      
   What about making m_psz a shared_ptr? It adds some overhead, sure.   
   But being able to share the member string buffer between multiple   
   immutable objects obviates the need for the move ctor, as the copy ctor   
   can just make the new object point to the same buffer as the copied-from   
   object.   
      
   cheers,   
   Martin   
      
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