Delphi TDictionary : values are replace automatically when have the same key - delphi

Question

I am using delphi XE5.
This a resume of my code, Next code works, but there have to be something in my code that destroy normal behaviour:
unit Class1;
type
TClass1 = class
private
FDic:TDictionary<String,String>.Create;
public
constructor create;
procedure insertValue(key,value:String);
end;
implementation
constructor TClass1.create;
begin
FDic:=TDictionary<String,String>.Create;
end;
procedure insertValue(key,value:String);
begin
if(FDic.ContainsKey(key))then
FDic[key] := value
else
begin
FDic.Add(key,value);
end;
end.
And now another unit:
unit Class2;
type
uses Class2;
TClass1 = class
public
class2 :TClass2;
TS: TStringList;
procedure DoSomething;
end;
implementation
procedure TClass1.DoSomething;
var
i: Integer;
c,test: TClass1;
begin
c := TClass1.create;
c.insertValue('height','.34cm');
c.insertValue('width','22cm');
c.insertValue('radio','2cm');
TS.AddObject('square',c);
c := TClass1.create;
c.insertValue('height','.88cm');
c.insertValue('width','11cm');
c.insertValue('top','12cm');
TS.AddObject('circle',c);
test := TS.Objects[0] as TClass1;//test.FDic height should be .34cm but gets the value of the last object create, the same for width an common keys.
//here when I look for the values of FDic test.FDic.Items['height'] the value is .88cm instead of .34cm, each time the values of any element of the Dictionary is replace with the previous of the last object created. And the memory address is the same. Why don't create a new memory address for any new element if it is a different object.
That is a resume of my code, I can put all my code because is too big, but I would like to know where I can search to resolve this problem. I am not is not easy, maybe I am not the only one with that problema, maybe some class in the uses, class variables, there is something that causes a memory problema in that dictionary, but no way to find it.

Answer 1

It's a little hard to be sure of the problem because you posted code that does not compile. For future reference, please don't do that. It's good to cut down the code to a small size, but you should then make it into a small console application that compiles and runs and demonstrates the fault. In spite of this, I think that I can see where the problem is.
You are creating objects and then adding them to a string list with
TS.AddObject(...);
But then you never free those objects. That, I guess, is the source of the leak. You can deal with this by setting the OwnsObjects property of the string list to True.
Specifies whether the string list owns the objects it contains.
The OwnsObjects property specifies whether the string list owns the
stored objects or not. If the OwnsObjects property is set to True,
then the Destroy destructor will free up the memory allocated for
those objects.
That I think will explain the leaks. The other part of your question is why index 0 contains the item that you added second. The only explanation for that, given the code in the question, is that your string list has the Sorted property set to True.
Again, I'm inferring this with a little intuition, but if you have only posted a complete program that compiled and run then your question could have been answered with complete certainty.
I do wonder whether or not a string list is the correct class to be using here. Perhaps you would be better with TObjectDictionary<string, TClass1>. You would create it like this:
dict := TObjectDictionary<string, TClass1>.Create([doOwnsValues]);
The use of doOwnsValues tells the dictionary that it is take assume ownership of the objects that you add as values and destroy them when they are removed from the dictionary, or when the dictionary is destroyed.
Note also that your insertValue method can be implemented in a far simpler way using the AddOrSetValue method.