IdThreadComponent (Indy 9) in Delphi 2007 Error - delphi

Question

I'm using IdTCPClient and IdThreadComponent to get some information for a barcode reader. This code, with some changes is working in Delphi 11 and Indy 10 but not in Delphi 2007 and Indy 9:
procedure TPkgSendF1.IdThreadComponent1Run(Sender: TIdCustomThreadComponent);
var
s: String;
begin
s := IdTCPClient1.ReadLn('&', 20000, 1500);
TThread.Queue(nil, procedure // <== Expected # but received PROCEDURE
begin
ProcessRead(s);
end);
end;
// [DCC Error] PkgSendF1.pas(239): E2029 Expression expected but 'PROCEDURE' found
procedure TPkgSendF1.ProcessRead(AValue: string);
begin
Memo1.Text := AValue;
end;
If I don't use the TThread.Queue I miss some readings.
I'll appreciate any help.
Francisco Alvarado

Answer 1

Anonymous methods did not exist yet in Delphi 2007, they were introduced in Delphi 2010. As such, TThread.Queue() in D2007 only had 1 version that accepted a TThreadMethod:
type
TThreadMethod = procedure of object;
Which means you need to wrap the call to ProcessRead() inside a helper object that has a procedure with no parameters, eg:
type
TQueueHelper = class
public
Caller: TPkgSendF1;
Value: String;
procedure DoProcessing;
end;
procedure TQueueHelper.DoProcessing;
begin
try
Caller.ProcessRead(Value);
finally
Free;
end;
end;
procedure TPkgSendF1.IdThreadComponent1Run(Sender: TIdCustomThreadComponent);
var
s: string;
begin
s := IdTCPClient1.ReadLn('&', 20000, 1500);
with TQueueHelper.Create do
begin
Caller := Self;
Value := s;
TThread.Queue(nil, DoProcessing);
end;
end;
FYI, Indy (both 9 and 10) has an asynchronous TIdNotify class in the IdSync unit, which you can use instead of using TThread.Queue() directly, eg:
uses
IdSync;
type
TMyNotify = class(TIdNotify)
public
Caller: TPkgSendF1;
Value: String;
procedure DoNotify; override;
end;
procedure TMyNotify.DoNotify;
begin
Caller.ProcessRead(Value);
end;
procedure TPkgSendF1.IdThreadComponent1Run(Sender: TIdCustomThreadComponent);
var
s: string;
begin
s := IdTCPClient1.ReadLn('&', 20000, 1500);
with TMyNotify.Create do
begin
Caller := Self;
Value := s;
Notify;
end;
end;