lyx_mirror/sigc++/doc/powerusers

The following things are be available to powerusers.

  - changing the return type of a slot
  - changing the paramete types of slot
  - signal overloading
  - mixed type signals

=======================================================================
* Slot type changing

Slots can be made to change their input types based on a static function.

Example:

  // write some conversion functions
  int convert_mysignal_c(Callback1<int,const char*> *s,const string &str)
    {return s->call(str.c_str());}
  Slot1<int,const string&> myconvert(const Slot1<int,const char*> &s)
    {return convert(s,convert_mysignal_c);}


  Signal1<int,const string&> mysignal;
  int foo(const char*);
  mysignal.connect(myconvert(slot(foo));


* Signal overloading

One signal can have multiple behavior for a single signal name.  
This is done with multiple inheritance.

Example:

  class MyClass
    {
      public:
        class MySig 
          :public Signal1<int,int>, 
           public Signal1<void,double>
         {} mysig;
   } myclass;

  int foo(int);
  void foo2(double);
  myclass.mysig.connect(slot(foo));
  myclass.mysig.connect(slot(foo2));
  myclass.mysig(1);   // calls foo
  myclass.mysig(1.0); // calls foo2

         

* Mixed type signals

A signal can be made to accept a wide group of slots with similar data
types.

Example:

  class A
    {

     public:
     class MySig: public Signal1<int,string&>
       {
          static int _mysig_convert(Callback1<int,const char*> *s,
                                    const string &str)
            {return s->call(str.c_str());}
        public:
          Connection connect(const Slot1<int,const char*> &s)
            {return connect(convert(s,_mysig_convert));}
       }  mysig;
    };

  int foo(const char* c);
  int foo2(string& s);

  mysig.connect(slot(foo));  // this is acceptable
  mysig.connect(slot(foo2)); // this is also acceptable
  string h="hello";
  mysig(h);                  // calls both foo and foo2.


Still in works
----------------
* Signal overloading over classes

This should be extendable accross different levels of a class.

Example: (details still in progress)

  

* Signals with translation

Signals can be made to convert and proxy accross other systems.