TFPGMap - does it free objects ?

[egsuh]

Simply checking...

In the case like

Code: Pascal  [Select][+][-]

1. type
2.    TaqVar = class
3.        ....
4.     end;
5.    TaqVarList = class(specialize TFPGMap<string, TaqVar>);
6.  
7. begin
8.     AqVarList := TaqVarList.Create;
9.  
10.     AQVar := TaqVar.Create;
11.     AqVarList.Add ('1', aqvar);
12.  
13.     AqVarList.Free;
14. end;

AFAIK I have to FREE aqvar MYSELF in the above case. Am I right?

[Thaddy]

For FGL
You should use TFPGMapObject with TFPGMapObject.Create(true);//owns objects/classes
See: https://www.freepascal.org/docs-html/current/rtl/fgl/tfpgmapobject.create.html
 
The standard map TFPGMap does not free objects.

For generics.collections you could use TObjectDictionary ( a map is the exact same as a dictionary )
example:

Code: Pascal  [Select][+][-]

1. {$ifdef fpc}{$mode objfpc}{$endif}
2. uses classes,fgl; // or generics.collections;
3. type
4.    TStrListMap = specialize TFPGMapObject<string,TStringlist>;
5.    // for rtl generics: TStrListMap = specialize TObjectDictionary<string,TStringList>;
6. var
7.    testmap:TStrListMap;  
8. begin
9.    testmap := TStrlistMap.Create(true);// owns objects
10.   // for ttl generics: TStrlistMap.Create([doOwnsValues]);
11.    try
12.      testmap.add('a',TStringlist.Create);
13.      testmap.add('b',TStringlist.Create);
14.      testmap.add('c',TStringlist.Create);
15.    finally
16.      testmap.free; // no leaks when the map is freed.
17.    end;
18. end.

[egsuh]

For FGL
You should use TFPGMapObject with TFPGMapObject.Create(true);//owns objects/classes
See: https://www.freepascal.org/docs-html/current/rtl/fgl/tfpgmapobject.create.html
For reference counted classes you could use TFPGMapInterfacedObjectData and add interface references.
 
The standard map TFPGMap does not free objects.

I know. I have several objects, which should be ordered in different ways.
So I have only one TFPGMapObject, and two TFPGMaps, all share the same objects.

[Thaddy]

Can't you solve that by using different enumerators?

[cdbc]

Hi

So I have only one TFPGMapObject, and two TFPGMaps, all share the same objects.

If I read you correctly, this organisation shouldn't pose any problem:
· they share the same objects ...an object can only be free'd once.
· so, you keep all your objects in the 'fpgobjectmap' which /owns/ them
· you fetch objects temporarily and keep them in the std. fpgmap for use
  (you are just borrowing them - no need to free)
· then you /borrow/ another set of objects and keep them in another fpgmap
  (again - no need to free them)
· in the end you're all done and the fpgobjectmap will free all objects...!
I don't see a problem in that 
...Otherwise you'll have to explain exactly what you're trying to do.
Regards Benny

[Thaddy]

What I mean is that you only need one list.
Suppose I want to access the list items in reversed order, you can do that like :

Code: Pascal  [Select][+][-]

1. // reverse access
2.    function reverseindex(const list:TStrlistMap; i:integer):integer;inline;
3.    begin
4.      result := pred(List.Count)-i;
5.    end;

Writing an accessor is more efficient than maintaining three lists.

[cdbc]

Hi
Yes, Thaddy, that's what I mean, there are other ways to achieve the end-goal...
He'll just have to explain what he wants...
Regards Benny

[egsuh]

I'll look for other ways, but this is weired.

Code: Pascal  [Select][+][-]

1. type
2.    TaqVarList = specialize TFPGMap<string, TaqVar>;
3.    TaqVarObjectList = specialize TFPGMapObject<string, TaqVar>;
4.  
5. var
6.    AVar: TaqVar;
7.    QVarList,
8.    VarList : TaqVarList;
9.    OrderedVarList: TaqVarObjectList;
10.  
11. begin
12.    QVarList := TaqVarList.Create;
13.    VarList := TaqVarList.Create;
14.    OrderedVarList:= TaqVarObjectList.Create;
15.    
16.     for ti := 0 to N do begin
17.          for tj := 1 to N2 [ti] do begin
18.               avar := TaqVar.Create;
19.               QVarList.Add(IntToStr(ti * N + tj), avar);
20.          end;    
21.          VarList.AddList(QVarList);
22.          QVarList.Clear;
23.     end;  
24.  
25.     OrderedVarList.AddList(VarList);   // this cause problem at CLOSING application.
26.  
27.      // but.. following does not cause problem.
28.      for i := 0 to VarLIst.Count - 1 do
29.           OrderedVarList.Add(VarList.Keys[i], VarList.Data[i]);
30.  
31.      // however, following CAUSE problem
32.  
33.      for i := 0 to VarLIst.Count - 1 do
34.           OrderedVarList.Add(NewOrderStr[i], VarList.Data[i]);  // the orders are changed here.  
35.  
36.      qvarlist.free;
37.      varlist.free;
38.      orderedvarlist.free;
39. end ;

Theoretically this should work correctly, which is not. I can find other way around, but hope anybody to check whether this is constant phenomenon. If yes, I think this is bug.

The problem is "Access violation" at the termimation of application. Not during run-time.

[cdbc]

Hi
Of course that should NOT work 
All the 'AVar' objects, you assign to a map that DOESN'T free objects!!!!!!!!
Only the accumulated lists you assign to an object-map, this /construct/ of yours will leak so hard, you might as well piss in your pants!!!
Back to the studying with you.
/bc

[egsuh]

They are freed by orderedvarlist. There are no leakages. Access Violation, I told.

[Thaddy]

The creation order is wrong. The ordered object map should be first created and last released.
And the constructor is not the correct constructor: TFpgMapObject.Create(true); otherwise the objects are not owned.

[egsuh]

I solved my own problem. I need further tests, but I think followings are bugs. Please read undefined variable names of my examples intuitively.

My situation is that my objects are created, but later I have to output them in different order from creation.

If defined as follow,

Code: Pascal  [Select][+][-]

1. type
2.      TMap = specialize TFPGMap<string, TAclass>;
3.      TObjMap = specialize TFPGMapObject<string, TAClass>;
4.  
5. var
6.     Map: TMap;
7.     ObjMap: TObjMap;
8.  
9. begin
10.     Map.Sorted := True;
11.     ObjMap.Sorted := True;
12.  

1.   TObjMap.AddList(TMap) does not work correctly. No compilation error, no runtime error but results are not what I expect.

Code: Pascal  [Select][+][-]

1.     ObjMap.AddList (Map);    // --> this does not work correctly.
2.  
3.      // Instead, I have to use
4.  
5.     for ti := 0 to Map.Count-1 do begin
6.          AClass := Map.Data[ti];
7.          ObjMap.Add(Map.Keys[ti], AClass);
8.     end;
9.  

2.   Either with TMap or TObjMap, reordering with the same objects cause problems. I mean "later problem", not at compilation or execution.  For example.

Code: Pascal  [Select][+][-]

1.     for ti := 0 to Map.Count-1 do begin
2.          AClass := Map.Data[ti];
3.          Map2.Add(NewOrderKey, AClass);   // NewOrderKey is a string. The whole order of list should be decided based on this.
4.     end;
5.  

executes well.  But it causes "Access Violation" at termination of application.


I have solved my own problem by mediating as follows.

Code: Pascal  [Select][+][-]

1.     for ti := 0 to Map.Count-1 do begin
2.          Map2.Add(NewOrderKey, Map.Key[ti]);
3.     end;
4.  
5.     // and later in use,
6.  
7.     for tj := 0 to Map2.Count-1 do begin
8.         AClass := Map.KeyData[Map2.Data[tj];
9.  
10.         // output AClass
11.    end;
12.  

[Thaddy]

You have

Code: Pascal  [Select][+][-]

1.     OrderedVarList.AddList(VarList);   // this cause problem at CLOSING application.

When adding a list, set it to unsorted, then sort.

[egsuh]

When adding a list, set it to unsorted, then sort.

Is duplication check possible with unsorted list?  Anyway this does not work either.

[Thaddy]

The problem is easier to remedy with rtl-generics, because that let's you choose if the keys and/or the values are owned.
But I am just guessing, because I have to turn your examples into compilable code every time.