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digitalmars.D.learn - Helper objects to create delegates

reply Jason House <jason.james.house gmail.com> writes:
I have a multi-threaded application where I pass delegates between 
threads.  While I thought this was a good design in the beginning, I 
find myself having to create a lot of helper objects...  Is there any 
way to avoid all the extra typing?  Any candidate additions to the 
language that'd help? :)

The following results in a run time error:
void example(){
   foreach(foo x; objectList)
     passDelegate({x.func(7);});
}

The following works but is annoying to keep typing:

class Helper{
   foo x;
   int param;
   this(foo _x, int _param){
     x     = _x;
     param = _param;
   }
   void opCall(){x.func(param);}
}
void example(){
   foreach(foo x; objectList)
     passDelegate(&(new Helper(x,7)).opCall);
}
May 30 2007
parent reply Daniel Keep <daniel.keep.lists gmail.com> writes:
Jason House wrote:
 I have a multi-threaded application where I pass delegates between
 threads.  While I thought this was a good design in the beginning, I
 find myself having to create a lot of helper objects...  Is there any
 way to avoid all the extra typing?  Any candidate additions to the
 language that'd help? :)
 
 The following results in a run time error:
 void example(){
   foreach(foo x; objectList)
     passDelegate({x.func(7);});
 }
 
 The following works but is annoying to keep typing:
 
 class Helper{
   foo x;
   int param;
   this(foo _x, int _param){
     x     = _x;
     param = _param;
   }
   void opCall(){x.func(param);}

{ return &(new Helper(x,param)).opCall; }
 }
 void example(){
   foreach(foo x; objectList)
     passDelegate(Helper.create(x,7));
 }

Like that? -- Daniel -- int getRandomNumber() { return 4; // chosen by fair dice roll. // guaranteed to be random. } http://xkcd.com/ v2sw5+8Yhw5ln4+5pr6OFPma8u6+7Lw4Tm6+7l6+7D i28a2Xs3MSr2e4/6+7t4TNSMb6HTOp5en5g6RAHCP http://hackerkey.com/
May 30 2007
parent Jason House <jason.james.house gmail.com> writes:
Daniel Keep wrote:
 
 Jason House wrote:
 I have a multi-threaded application where I pass delegates between
 threads.  While I thought this was a good design in the beginning, I
 find myself having to create a lot of helper objects...  Is there any
 way to avoid all the extra typing?  Any candidate additions to the
 language that'd help? :)

 The following results in a run time error:
 void example(){
   foreach(foo x; objectList)
     passDelegate({x.func(7);});
 }

 The following works but is annoying to keep typing:

 class Helper{
   foo x;
   int param;
   this(foo _x, int _param){
     x     = _x;
     param = _param;
   }
   void opCall(){x.func(param);}

{ return &(new Helper(x,param)).opCall; }
 }
 void example(){
   foreach(foo x; objectList)
     passDelegate(Helper.create(x,7));
 }

Like that? -- Daniel

... or very similar. I think I mean to do passDelegate( &(new Helper(x,7)).opCall ); I found std.bind which provides the functionality I was looking for. The .ptr() threw me for a loop, but I have it down now. passDelegate( bind(&x.func,7).ptr() );
May 31 2007