Jonas Maebe wrote:
If you had two different create constructors (for whatever reason),
might you not also need two different destroy destructors?
No, the default destructor should always free all resources,
regardless of how the class instance was created. Otherwise, it would
also make your c
On 4/3/09, Doug Chamberlin wrote:
> Essentially, yes.
>
> However, you may create subtle, lurking bugs if you omit that call and
> later refactor your code. For example, if you later change
>
> type
> TFoo = class
>
> to
>
> type
> TFoo = class(TSomeClass)
>
> and TSomeClass has so
Bart wrote:
On 4/3/09, Jonas Maebe wrote:
I think what is meant, is that if you create a direct subclass of TObject,
there is no need to call TObject's create constructor (e.g., via "inherited
create;") from your own constructors. It doesn't hurt if you do it of
course, and may be good practic
On 03 Apr 2009, at 16:21, Bart wrote:
So if i understand correctly:
Say I have
Type
TFoo = class;
private
fSomeField: Integer;
public
constructor Create;
end;
then
constructor TFoo.Create
begin
Inherited Create;
fSomeField := -1;
end;
would in essence be equal to
constructor TFoo.Cr
On 4/3/09, Jonas Maebe wrote:
> I think what is meant, is that if you create a direct subclass of TObject,
> there is no need to call TObject's create constructor (e.g., via "inherited
> create;") from your own constructors. It doesn't hurt if you do it of
> course, and may be good practice to ac
> C) Just out of curiosity, am wondering why FreeAndNil is global procedure
> instead of a method/destructor of TObject. I am guessing it is
> for compatibility with Delphi which may or may not have a reason?
A method could not act the way FreeAndNil works (zeroing a local
pointer variable). It
On 03 Apr 2009, at 03:43, Richard Ward wrote:
A) The documentation says that for the create constructor:
(quote}
Description: Create creates a new instance of TObject. Currently it
does nothing. It is also not virtual, so there is in principle no
need to call it directly.
{unquote}
On 03 Apr 2009, at 03:43, Richard Ward wrote:
5) Although I can't remember reading it anywhere, I've noticed from
my own demo programs that the addresses of objects are initially set
to nil.
That is not correct. All global variables (classes/objects or not) are
initialized to 0/nil, but
On 03 Apr 2009, at 03:43, Richard Ward wrote:
C) Just out of curiosity, am wondering why FreeAndNil is global
procedure instead of a method/destructor of TObject.
If you have:
var
c: tsomeclass;
begin
c:=c.tsomeclass.create;
c.freeandnil
end;
then freeandnil would get, as first (hidd
> What is it meant by: "no need to call [create] directly?" How do you
> invoke the constructor without calling it? ... and ... Why is create
> not virtual and the destroy destructor is?
Often in other OOP language, you need to call parent constructor before
doing anything else. In OP case,
I am a little bit unclear about certain things on class constructors
and destructors.
From what I read in the language reference guide (chapter 6) and
runtime utilities document (chapter 29):
1) All classes descend from TObject; even declaring a new class
without using TObject as a qualif
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