CODEWITHSUNDEEP
delphiobjectarraylistfreedelphi-prism
ThN
ThN

Reputation: 3278

How to free an arraylist of objects in a Delphi Prism?

I need to free list of objects stored in an ArrayList. I know you can call Free procedure in Delphi, but in Delphi Prism there is no free procedure. I don't just want to remove objects from the list but also free it from its memory.

For instance Say I have this following class

TheClass = Class
 private
 theStr:String;
 protected
 public
end;

method TheForm;
begin
 TheArrayList:=new ArrayList;
end;

To Add Object I would do this:

method TheForm.AddToList;
var
 tmpObj:TheClass;
begin
 tmpObj := new TheClass;
 TheArrayList.Add(tmpObj);
end;

To Delete Object from the list, this is how I would do it but there is no free procedure.

method TheForm.DeleteFromList;
var I:integer;
begin
 for I:=0 to theArrayList.count-1 do
 begin
  theClass(theArrayList[I]).free;     <-------I know this doesnt work.
  theArrayList.RemoveAt(I);
 end;
end;
end;

How is freeing list of object accomplished in Delphi Prism?

Thanks,

Upvotes: 2

Views: 691

Answers (3)

Rudy Velthuis
Rudy Velthuis

Reputation: 28806

Delphi Prism programs run on .NET. There is no need to free any objects, since the garbage colleector will eventually do that. As someone already commented, you can call IDisposable.Dispose() to free other resources than memory, if the object implements it.

There is also the using construct, which is a bit like Create-try-finally-Free-end in Delphi:

using MyArrayList = new ArrayList do
begin
  // use ArrayList...
end; // IDisposable(ArrayList).Dispose is called, if applicable.

This won't work for the items in the array, of course. If you really want, you can call Dispose on each of them. But generally, this is not necessary.

So:

method TheForm.DeleteFromList;
begin
  theArrayList.Clear;
end;

No need to free anything.

Upvotes: 1

David Heffernan
David Heffernan

Reputation: 612794

Since your class is not holding onto any unmanaged resources like files, window handles, database connections etc. you need do nothing beyond letting the .net garbage collector free the memory when it decides the time is right.

Trying to force the garbage collector to run ahead of time typically leads to worse performance than simply letting it do its job.

If you had a class with unmanaged resources then you should follow the IDisposable pattern.

Upvotes: 4

TheHorse
TheHorse

Reputation: 2797

while theArrayList.count > 0 do
  theArrayList.RemoveAt(0);

GC will help you.

Upvotes: 1

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