how to add a ForEach call to TFPGList

[mas steindorff]

I see the TFPList has a .ForEachCall() procedure
is it hard to add this to a TFPGList?

I'm looking for a cleaner way to loop though each item I've defined as a class and call it's .ClearHand() procedure without a for loop.

[cdbc]

Hi
  1)

Code: Pascal  [Select][+][-]

1. TListCallback = procedure(data,arg:pointer) of object;  // TFPList

1.1)

Code: Pascal  [Select][+][-]

1. TGListCallback = procedure(data,arg:<T>) of object;  // TFPGList

 

  2)

Code: Pascal  [Select][+][-]

1. procedure ForEachCall(proc2call:TListCallback;arg:pointer);

2.1)

Code: Pascal  [Select][+][-]

1. procedure ForEachCall(proc2call:TGListCallback;arg:<T>);

  3)

Code: Pascal  [Select][+][-]

1. procedure TFPGList.ForEachCall(proc2call:TGListCallback;arg:<T>);
2. var
3.   i : integer;
4.   p : T;
5. begin
6.   For I:=0 To Count-1 Do
7.     begin
8.       p:=FList^[i];
9.       if assigned(pointer(p)) then
10.         proc2call(p,arg);
11.     end;
12. end;

Maybe something like the above :: It is untested code, just my first stab at it... Perhaps you can implement it in a descendant class...
Regards Benny

[jamie]

There is already a enumerator in that generics, just encase it with a inline function.
Jamie

[mas steindorff]

Thank you Benny,
I'll give the code you posted a try

Jamie, I'm afraid your post is over my head so I've been looking around at your other post for more info. I also looked into the header of TFPGList but did not find any ForEach... calls to "inline"??
can you point me to a code example you are recommending I try?
 

Thank you both for your post. This project goal is for me to learn and both post are firing the brain cells.
Mas

[cdbc]

Hi Mas
I think jamie means something like this:

Code: Pascal  [Select][+][-]

1. generic procedure FPGList_ForEachCall(aList: TFPGList;
2.   proc2call:TGListCallback;
3.   arg:<T>); inline;
4. var
5.   i : integer;
6.   p : T;
7. begin
8.   For I:=0 To aList.Count-1 Do
9.     begin
10.       p:=aList^[i];
11.       if assigned(pointer(p)) then
12.         proc2call(p,arg);
13.     end;
14. end;

I could ofc. be mistaken...
Regards Benny

[jamie]

I'll try to make this simple for you

Code: Pascal  [Select][+][-]

1.  
2. var
3.  YourClass:TMyCalssThatIsStoredInMyTFPGLIST;
4. Begin
5. For yourClass In MyInstanceOfTheTFPLIST do
6.   YourClass.ClearHand;
7. End;
8.  

 That will loop through all the classes you have stored in the TFPGLIST without using indexes etc.

You can incapsulate that within a Procedure to make it easier for you.

Code: Pascal  [Select][+][-]

1. Procedure ClearAllHands;
2. /// Encapsulate above code here;
3. End;
4.  

basically, the compiler will create a Enumerator class in the background and free it when the FOR LOOP is completed.

This Enumerator will return a class instance starting from the first one to the last one.



Jamie

[mas steindorff]

thank you, now I understand.
I would have called this a pascal "set" or use of "in" approach.  I just need to update my vocabulary.
Mas