Re: Problem using STL list and map objects as static member variables

From:
"mlimber" <mlimber@gmail.com>
Newsgroups:
comp.lang.c++
Date:
21 Jul 2006 13:04:42 -0700
Message-ID:
<1153512282.342605.293220@75g2000cwc.googlegroups.com>
Bit byte wrote:

I am writing a small parser object. I need to store keywords etc in
lsts. Because this data is to be shared by all instances of my parser
class, I have declared the variable as class variables (i.e. statics).

//declarations in parser class (private section)
static list<string> m_keywords, m_symbols_used;
static map<string, myParser::FuncData> m_mapped_funcs ;

I have initialization code like this:

    m_symbols_used.clear();

    //loadup keywords
    m_keywords.clear()
    m_keywords.push_back(ABC) ;
    m_keywords.push_back(CDE) ;

    ...

I obviously can't place this in the constructor since they are statics -
(actually, I tried but I had linkage errors). Any ideas as to how to
initialize these variales ?


Use an initializer helper class:

 class A
 {
 public:
   // ...
 private:
   static const std::map<int,const char*> map_;
 };

Then in your .cpp file:

 namespace // anonymous
 {
   template<class Key, class Value>
   class MapInitializer
   {
     std::map<Key,Value> m_;
   public:
     operator std::map<Key,Value>() const { return m_; }

     MapInitializer& Add( const Key& k, const Value& v )
     {
       m_[k] = v;
       return *this;
     }
   };
 }

 const std::map<int,const char*> A::map_
   = MapInitializer<int,const char*>()
     .Add( 10, "Msg 1" )
     .Add( 20, "Msg 2" )
     .Add( 30, "Msg 3" );

Cheers! --M

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