Re: std::list with const and non-const pointers - why aren't they type compatible?

* arijit79@gmail.com:


That would allow you to change a constant object, like e.g.

    char const* const s = "puck";

    std::list<char*> varList;
    std::list<char const*>& constList = varList; // !Not allowed

    constList.push_back( s );
    char* const p = *varList.begin();
    p[0] = 'f';


You're providing too little information to give any definite answer -- see the
FAQ about How To Post.

However, it does *seem* as if you're missing three important concepts and have
one misconception, none of them directly related to the 'const' issue:

   * Probably missing, the concept of referring to something (via a pointer or
     C++ reference doesn't matter in that respect). Reasons that it's probably
     missing: having a list of raw pointers, returning a result by reference.

   * Probably missing, the concept of object lifetime. Reason it's probably
     missing: returning by reference.

   * Probably missing, the concept of Return Value Optimization (RVO). Reason
     it's probably missing: returning by reference.

   * Probable misconception, that micro efficiency matters a lot. Reason it's
     probably there: returning by reference, using a list of raw pointers.

If so the only cure is experience coupled with correct information (e.g. a good
book, or for that matter Usenet discussions).

But one doesn't always need to know the details of what's wrong in order to
suggest a cure.

In the only example you've given I suggest using std::list< std::string >, and
return that type directly (not tacking on a '&' at the end).

Cheers & hth.,

- Alf

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