Re: Intit an Array of objects with ctor

From:
"Daniel T." <daniel_t@earthlink.net>
Newsgroups:
comp.lang.c++
Date:
Sat, 27 Mar 2010 22:06:39 -0400
Message-ID:
<daniel_t-1A9645.22063827032010@70-3-168-216.pools.spcsdns.net>
peterfarge <peterfarge@gmx.de> wrote:

I need a hint: I want to create a game map. Every place on this map is
a PlaceClass. This PlaceClass has one ctor with a pointer to a init
object. Now I want to create my map as a 2D of PlaceClass

class Map {
public::
 Map(cInit *ptrInitObj) : m_map[100][100](ptrInitObj) { // <-- How to
init the array?
 }

private:
 PlaceClass m_map[100][100];
};


I would do it more like this:

// see "The C++ Programming language" section 24.3.7.2 for other options
inline void Assert(bool pred, const char* file, int line) {
   if (!pred) {
      std::stringstream ss;
      ss << "logic error at: " << line << "in file: " << file;
      throw std::logic_error(ss.str());
   }
}

class cInit { };

class PlaceClass {
public:
   PlaceClass(const cInit& initObj);
};

class Map {
   std::vector<PlaceClass> m_map;
   PlaceClass& at(int x, int y) {
      Assert(0 <= x && x < 100, __FILE__, __LINE__);
      Assert(0 <= y && y < 100, __FILE__, __LINE__);
      return m_map[y + x * 100];
   }
public:
   Map(const cInit& initObj): m_map(1000, PlaceClass(initObj)) { }
};

Now, instead of "m_map[x][y]" inside the code, do "at(x, y)". Note that
the 'at' function is private so that encapsulation is not broken.

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