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DDE.SetLink fails if running in a new thread

I'm trying to use DDE.SetLink within a new thread, but the call fails right away, while it works normally if I don't do it threaded. What is wrong?

function mIRCinfo(P: Pointer) : LongInt; stdcall;
var DDE: TDDEClientConv;
begin
  try
    DDE := TDDEClientConv.Create(nil);
    if DDE.SetLink(mIRCSet.Service, mIRCSet.Topic) then
    begin
     DDE.OpenLink;
     DDE.PokeData(mIRCSet.Topic, PChar(mIRCSet.Command));
     DDE.CloseLink;
    end
    else
      showmessage('fail');
  finally
    DDE.Free;
  end;
end;
 
 
 
Var    thr : THandle;
          thrID : DWORD;
 
   thr:= CreateThread(nil, 0, @mIRCinfo, nil, 0, thrID);

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2266180

you need to call coinitialize and cofinalize when the thread starts, respectivly ends, from the created thread. in your case, use another try finally which will incorporate the 2 calls.

bryan7

ASKER

it still fails

function mIRCInfoThreaded(P : Pointer): LongInt; stdcall;
var DDE: TDDEClientConv;
begin
 try
   CoInitialize(nil);
  try
    DDE := TDDEClientConv.Create(nil);
    if DDE.SetLink(mIRCIntoSet.Service, mIRCIntoSet.Topic) then
    begin
     DDE.OpenLink;
//     DDE.PokeData(mIRCIntoSet.Topic, PChar(mIRCIntoSet.Command));
     DDE.CloseLink;
    end
    else showmessage('Failed to stablish link with DDE');
  finally
    DDE.Free;
  end;
 finally
   CoUninitialize;
 end;
end;

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2266180

what about:

uses ..., ActiveX;
 
....
 
function mIRCInfoThreaded(P : Pointer): LongInt; stdcall;
var DDE: TDDEClientConv;
begin
 try
   CoInitializeEx(nil, 0);
  try
    DDE := TDDEClientConv.Create(nil);
    if DDE.SetLink(mIRCIntoSet.Service, mIRCIntoSet.Topic) then
    begin
     DDE.OpenLink;
//     DDE.PokeData(mIRCIntoSet.Topic, PChar(mIRCIntoSet.Command));
     DDE.CloseLink;
    end
    else showmessage('Failed to stablish link with DDE');
  finally
    DDE.Free;
  end;
 finally
   CoUninitialize;
 end;
end;

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bryan7

ASKER

Same result, SetLink fails.

2266180

can you post a zip with a small demo which has this behaviour so I have something to work with?
thanks

bryan7

ASKER

Open a new project, and simple paste the 2 functions and the code on form create:

You'll have to enable DDE in mirc, in Options, Other, DDE, "Enable DDE Server"

Then oncreate, you'll the non-threaded one works, and the other one fails.

unit Unit5;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ActiveX, ddeman;
 
type
  TForm5 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form5: TForm5;
 
implementation
 
{$R *.dfm}
 
function mIRCInfoThreaded(P : Pointer): LongInt; stdcall;
var DDE: TDDEClientConv;
begin
 try
   CoInitializeEx(nil, 0);
  try
    DDE := TDDEClientConv.Create(nil);
    if DDE.SetLink('mIRC', 'COMMAND') then
    begin
     DDE.OpenLink;
     DDE.CloseLink;
     showmessage('thread: this works');
    end
    else showmessage('thread: Failed to stablish link with DDE');
  finally
    DDE.Free;
  end;
 finally
   CoUninitialize;
 end;
end;
 
procedure mIRCInfoNotThreaded;
var DDE: TDDEClientConv;
begin
  try
    DDE := TDDEClientConv.Create(nil);
    if DDE.SetLink('mIRC', 'COMMAND') then
    begin
     DDE.OpenLink;
     DDE.CloseLink;
     showmessage('no thread: this works');
    end
    else showmessage('no thread: Failed to stablish link with DDE');
  finally
    DDE.Free;
  end;
end;
 
procedure TForm5.FormCreate(Sender: TObject);
Var thr : THandle;
    thrID : DWORD;
begin
  thr:= CreateThread(nil, 0, @mIRCinfoThreaded, nil, 0, thrID);
  mIRCInfoNotThreaded;
end;
 
end.

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bryan7

ASKER

Typo: "you'll see". How come there is no edit function ;(

ASKER CERTIFIED SOLUTION

2266180

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bryan7

ASKER

I see. Guess I'll just leave it be then and use the old way. Thanks!

2266180

B grade? I solve your problem correctly, give you alternative solutions, and you give me a B grade? Guess you didn't read the FAQ and help section not to mention the grading tips.

no problem, you just made it on my blacklist which basically means that I will no longer answer any of your questions.

no need to anwser as I've unsubscribed.

enjoy.

bryan7

ASKER

I doubled the points instead so you got more points than you would otherwise with the original points*A