Can anyone explain why this program doesn’t capture the state of the local
variable “I” and execute in order? It will return something like this:
Invoked: 3 id: 00000001029D41C0
Invoked: 0 id: 00000001029D42C0
Invoked: 0 id: 00000001029D44C0
Invoked: 0 id: 00000001029D43C0
It works if you call Start directly before WaitFor, but why? I would expect the
function reference to capture i, start the thread and then block the program
after the sleep calls but instead the sleep calls appear to do nothing and the
program exists immediately.
=================================
{$mode objfpc}
{$modeswitch anonymousfunctions}
{$modeswitch functionreferences}
{$modeswitch arrayoperators}
program test;
uses
Cthreads, SysUtils, Classes;
type
TProc = reference to procedure;
TCallback = class(TThread)
private
proc: TProc;
public
constructor Create(p: TProc);
procedure Execute; override;
end;
procedure TCallback.Execute;
begin
proc();
Sleep(100);
end;
constructor TCallback.Create(p: TProc);
begin
inherited Create(true);
proc := p;
end;
var
i: integer;
callback: TCallback;
callbacks: array of TCallback = ();
begin
for i := 1 to 4 do
begin
callback := TCallback.Create(procedure
begin
writeln('Invoked: ', i, ' id: ',
HexStr(TThread.CurrentThread));
end);
callback.Start;
callbacks += [callback];
end;
for i := 0 to High(callbacks) do
callbacks[i].WaitFor;
end.
Regards,
Ryan Joseph
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