[fpc-pascal] methods of an object to create others objects

[Michael Van Canneyt]

On Mon, 5 Jul 2010, Graeme Geldenhuys wrote:

> On 5 July 2010 22:03, Marcos Douglas wrote:
>> The ask is:
>> If a function creates, inside, a object and there is no variable to
>> receive this pointer, will happen a memory leak?
>
> Yes you will have a memory leak. Easy way to test is to enable the
> heaptrc unit (compiler option -gh). On terminating the application,
> the heaptrc unit will dump memory usage output to the console window.
>
> If the object returned is a reference counted object, then I think it
> will be freed (though not working with the interface instance itself
> is bad practice).
>
> Remember FPC doesn't have garbage collection like Java or .NET.  Rule
> of thumb is that if you created it, you need to free it.

I would even add to this that you need to guard for exceptions:

A:=TSomeClass.Create;
try
   // do stuff
finally
   A.Free; Make sure it is freed, even in case of exception.
end;

If your classes have more global scope, rule of thumb is to create objects
in the form/datamodule's OnCreate event, and to free them in the OnDestroy
event. (I always code the create and free statements together, so as not to
forget this).

Michael.