BorlandTalk.com

server · Guest

message unavailable

Peter Morris [Droopy eyes · Guest

David M · Guest

Jeremy · Guest

Thanks for pointing me to MVP. I'd seen this mentioned before, but somehow
couldn't help thinking it had something to do with the poster's
qualifications (g).

If I understand MVP's goal, it seems to be more than I want to do at the
moment. I don't mind if we need to rewrite the presentation layer stuff so
long as we don't have 2 code bases for the business logic. However, even
this simpler problem has proved to be too much for my little pea brain. It
sounds really simple -- just write some dlls and keep forms and dialogs out
of it, but the interactions begin to look like spaghetti. For the moment I
think I need to press on and get the functionality into final test and
production, and worry about this problem when the brain swelling goes down
and the toolset matures.

Jeremy

"Jeremy" <jeremy> wrote in message news:43d914ba$1 (AT) newsgroups (DOT) borland.com...

Graeme Geldenhuys · Guest

Joanna Carter [TeamB] wrote:

Jim Cooper · Guest

Dave Champion · Guest

Andrea Raimondi · Guest

First thing: IMHO, this message belongs to .oodesign group.
Short summary of the thread: the OP wants to dynamically
bind his forms to his datasets.
This is basically wrong, imho, unless the datasets are
surfacing an OPF.
Example code that was posted in the thread:
"
MainDM.QBirim.Locate(dgdataDBTableView1.Columns[0].DataBinding.FieldName,
mnuDbSearch.CurText, [loCaseInsensitive, loPartialKey]);

MainDM is my Datamodul
and QBirim is my Tadoquery

I want use a general definiton
MyFormQuery : TAdoquery

MainDM.XXXXXXXX.Locate(dgdataDBTableView1.Columns[0].DataBinding.FieldName,
mnuDbSearch.CurText, [loCaseInsensitive, loPartialKey]);

If my MyFormQuery is QBlabla this lines will be

MainDM.QBlabla.Locate(dgdataDBTableView1.Columns[0].DataBinding.FieldName,
mnuDbSearch.CurText, [loCaseInsensitive, loPartialKey]);
"

Ardahan wrote:

Ardahan · Guest

Thanks Andrew, I will watch my thread from here. If anybody can send me an
example project I will be happy.

Thanks for all persons because you are sharing your experiences with us.

"Andrea Raimondi" <rainaple (AT) tin (DOT) it>, haber iletisinde sunlari
yazdi:43ee7ff5$1 (AT) newsgroups (DOT) borland.com...

Nicolai Waniek · Guest

Joanna Carter [TeamB] wrote:

en see how it goes Smile

)

pcplayer · Guest

Hi,

I have the same problem.

Through my test, if a class is a descendent class of TInterfacedObject
and implement a Interface, and if you use it's interface, if you free
it , you will get a AV error.

I write a class named TMyInterfacedObject, it just like
TInterfacedObject, and I Update this code:

function TInterfacedObject._Release: Integer;
begin
Result := InterlockedDecrement(FRefCount);
if Result = 0 then
Destroy;
end;

To:

function TMyInterfacedObject._Release: Integer;
begin
Result := InterlockedDecrement(FRefCount);

//if Result = 0 then
// Destroy;
end;

So, if I release all the interface ref, the class will not free it's
self.

The next step of my test is:

I make a new class descendent from TMyInterfacedObject:

ILjnInt=interface
['{90C24D7C-EBEF-43E0-9B57-43AD11733866}']
procedure Hello(S:string);
end;

TLjnClass=class(TMyInterfacedObject,ILjnInt)
public
FMyInt:ILjnInt;
constructor Create;
destructor Destroy;override;
procedure Hello(S:string);
end;

Then, I use this class like:

MyClass:=TLjnClass.Create;
MyInt:=ILjnInt(MyClass);
MyInt.Hello('abcdefg');
MyInt:=nil;
MyClass.Free;

Ha, there is no problem.

if I have not do MyInt:=nil, MyClass.Free will cause AV error.

conclusion: if you get a interface Ref. of a Interfaced Object, and
have not set it to nil, execute this class's Free method will cause AV
error. if you free all interface Ref. of this object, you can free it
with no error.

But, why ? How can I change this behavior through change the source
code of TInterfacedObject ?

It seems no way ?

pcplayer · Guest

try again....

In my test below, I found that I can Free a Object while it's
Interface's Ref. more than one.

First, I declare a class just like TInterfacedObject:

TLjnInterfacedObject = class(TObject, IInterface)
protected
FRefCount: Integer;
function QueryInterface(const IID: TGUID; out Obj): HResult;
stdcall;
function _AddRef: Integer; stdcall;
function _Release: Integer; stdcall;
public
procedure AfterConstruction; override;
procedure BeforeDestruction; override;
class function NewInstance: TObject; override;
property RefCount: Integer read FRefCount;
end;

all implementation of this class just copy from TInterfacedObject,
only:

function TLjnInterfacedObject._Release: Integer;
begin
{Result := InterlockedDecrement(FRefCount);
if Result = 0 then
D estroy;
} <-----------This code is copy from TInterfacedObject, I comment
it.

Result:=-1; //<----- this code is add by me.
end;

the second, I declare a class like this:

ILjnInterface=Interface
procedure Hello(S:string);
end;

TLjnObj=class(TLjnInterfacedObject,ILjnInterface)
public
procedure Hello(S:string);
end;

and the third, I use the TLjnObj to test it:

procedure TForm1.Button1Click(Sender: TObject);
var
MyObj:TLjnObj;
MyInt:ILjnInterface;
MyCom:TComponent;
i:Integer;
S:string;
begin
1. MyObj:=TLjnObj.Create;

2. MyInt:=ILjnInterface(MyObj);

{
3. i:=MyObj.RefCount;
4. S:=IntToStr(i);
5. Memo1.Lines.Add(IntToStr(i));
}

6. MyInt.Hello('haha');

7. //MyInt:=nil;

8. MyObj.Free;
end;

In this code, I used the MyInt:ILjnInterface, and I didn't set it to
nil ( on line 7), and on line 8, I free MyObj. It's no problem! There
is no AV error!

But, if I let the line 3, 4, 5 execute, It will cause AV error. It's so
strange.

If I let line 3,4,5 execute, and the same time do line 7: MyInt:=nil,
there is no AV error.

So, if use a object's interface and you have not set it to nil when you
FreeAndNil the object, it is ok, but this time you must not read the
object's RefCount method otherwise you will get a AV error.

Dave Keighan · Guest

Bob,

In the "About Entity-Relationship Diagram in BDS 2007" thread in borland.public.delphi.non-technical you, Jim Cooper and Joanna Carter have all made comments about not using an OPF that streams objects to Blobs [ .... or to that effect Jim Smile

]. Jim and Joanna have rolled their own - you haven't indicated what you use, not that it's important to my question(s). I think the three of you have an extremely valid point here and would like [you] to discuss it more ... just not in /that/ thread :)

Jim Cooper · Guest

Dave Keighan · Guest

Jim,

Thanks for taking the time to respond.