Remy Lebeau

There is no ETA on when Indy 11 will be released. Work on it has been slow for several years, but there has been work on it nonetheless. There is an Indy11-preparation branch in Indy 10's GitHub repo whose code is expected to eventually become Indy 11, but it is not quite ready for release yet.

In which case, I wouldn't even bother with calling Application.Terminate(), just skip calling Application.Run() instead: begin Application.Initialize; Application.ShowMainForm := False; Application.CreateForm(TfrmMainForm, frmMainForm); if frmMainForm.DoWeShowTheForm then begin Application.ShowMainForm := True; Application.Run; end; end.

Application.Terminate() calls PostQuitMessage() internally: // ----- Form1 ---- uses Unit2; procedure TForm1.FormCreate(Sender: TObject); begin Application.Terminate; end; procedure TForm1.Button1Click(Sender: TObject); begin Form2 := TForm2.Create(self); end; // ----- Form2 ---- procedure TForm2.FormCreate(Sender: TObject); begin Application.Terminate; end; No need for using OnClose/caFree when Form1 is the Owner of Form2, since Application.Terminate()/PostQuitMessage() is asynchronous, so the Form1 and Form2 objects will still be created, Form1 will take ownership of Form2, and then the Application object will destroy the Form1 object, and thus the Form2 object, when the Application object is destroyed after the quit message makes Application.Run() exit.

Note that such usage is demonstrated in Embarcadero's documentation, though it is not explicitly called out as being a requirement: https://docwiki.embarcadero.com/RADStudio/en/Inline_Variable_Declaration procedure Test99; begin // some code if (something) then begin var Intf: IInterface = GetInterface; // Intf.AddRef // <-- HERE! var MRec: TManagedRecord = GetMRecValue; // MRec.Create + MRec.Assign UseIntf(Intf); UseMRec(MRec); end; // Intf.Release and MRec.Destroy are implicitly called at end of scope // more code end; // no additional cleanup

Only while the control is actively processing a paint operation invoked by the OS - ie, during a WM_PAINT or NM_CUSTOMDRAW or equivalent window message. Before the control's virtual Paint() method is called, or its public OnPaint/OnDraw... events are fired, both allowing user code to handle custom drawing, the relevant control properties are assigned to the Canvas. Outside of an active paint operation, the Canvas's properties are not guaranteed to match the control's properties, and likely will be defaults instead.

AFAIK, yes, it is still the case.

IsNullOrEmpty() is a method of TStringHelper, so you have to call it on a string instance, eg: if MyTable.FieldByName('MyField').AsString.IsNullOrEmpty then Which is really no better than simply testing for an empty string (since AsString can't return a null string): if MyTable.FieldByName('MyField').AsString = '' then However, since Delphi strings don't differentiate between null and empty (they are both a nil pointer), if you really need to differentiate then you will have to use TField.IsNull instead, eg: if MyTable.FieldByName('MyField').IsNull then // is null ... else if MyTable.FieldByName('MyField').AsString = '' then // is empty ... else // is not null or empty ...

Are you using the Feature installer (Web) or the Offline installer (ISO)?

Note that TCP is usually not a good choice for streaming media, due to delays caused by latency, integrity checks, acks, etc. TCP is good to use when you need to ensure the receiver actually gets everything that is sent. But since real-time streaming media doesn't usually require that, dropped packets here and there are usually tolerable, so UDP is used instead, typically with a streaming media protocol on top of it, like RTP, etc.

Delphi ships with Indy pre-installed, which has a TIdHTTP component. Modern versions of Delphi also have native THTTPClient/TNetHTTPClient components, too. But either way, you can't just send arbitrary data to the ESP without understanding what it is actually expecting. Do you have any documentation on what exactly it actually wants clients to send it? What do the required URLs look like? What input parameters are they expecting? Are they query-string parameters, or post-body parameters? Etc

The OS is not involved in this process. Instantiating an object is simply a matter of allocating a memory block to hold the data members, and then calling the class constructor on that memory block to initialize the data members. Any methods called on an object (including the constructor and destructor) is simply a matter of making a normal function call with a pointer to the object as a (hidden) parameter so the code knows which object is being act on. There are no copies of the method instructions being made. There is only 1 copy in memory that all objects share. Calling the same method on multiple objects will execute the same code instructions just with a different object parameter. It will fail if the patched method tries to access any data members that don't actually belong to the actual object that the method is being called on.

Using the Addr() intrinsic in that way will give you the memory address of the _TaskDialogIndirect variable itself, not the memory address that the variable holds. Try inspecting just _TaskDialogIndirect by itself, or at least cast it to a Pointer.

It is not an implementation detail, it is documented behavior: https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessa https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessw

That means you are trying to call a function through a nil function pointer. Did you check to see whether _TaskDialogIndirect is nil or not?

Incorrect, it is the 2nd argument that must be writable. And only in the Unicode version.

There is also ShowMessagePos() for that purpose.

INVALID_HANDLE_VALUE is not null (0), it is -1. Some APIs return 0 on failure, some return -1 instead. Be careful mixing them up. See Why are HANDLE return values so inconsistent?

The point I was trying to make is that, if InternetOpen() fails, the value of HFile is left indeterminate, so calling InternetCloseHandle() on it is undefined behavior. Also, InternetCloseHandle() is not documented as accepting null handles, so if either InternetOpen() or InternetOpenUrl() fails, calling InternetCloseHandle() on the failed handle is also undefined behavior. So, best to call InternetCloseHandle() only on successfully opened handles. Which means, using multiple try..finally blocks. Calling GetLastError() multiple times mixed in other system calls risks having the error code wiped out in between the calls. Best to save the error code to a variable as soon as possible, and then use the variable where needed. Yes. Which is why one should generally use WriteBuffer() instead, which will raise if not all bytes are written.

This code has many small mistakes. Too many try's. Undefined behavior calling InternetCloseHandle() on invalid handles if either InternetOpen() or InternetOpenUrl() fail. Misuse of GetLastError(). Not reporting an error if InternetReadFile() fails. Not making sure FBuffer actually writes all of the bytes it is given.

Not a copy, but the original. All object instances of a class have their own copies of data members, but they all share a single set of code, vtables, etc in memory. So, patching a method of a class will affect all object instances of that class. Not sure I understand what you are asking.

It raises an exception on error. However, internally it uses Windows' Urlmon.URLDownloadToFile() function, which is notoriously buggy, and crappy at reporting errors.

No. First, not even considering threads yet, TApplication is simply not designed to run multiple instances at a time. There are globals that it uses internally which it assumes it has exclusive access to, and will not share well with other instances. Also, there is plenty of code inside of the VCL that assumes there is only 1 global TApplication object, and won't even consider the existence of other instances. Second, considering threads, the VCL is simply not thread-safe to begin with. It is not designed to be used in multiple threads at a time. VCL controls are expected to be used only in the main UI thread which runs the single global TApplication object. Also, the VCL runs on top of the Win32 API, and API window handles have an affinity to the thread that creates them, which restricts which threads are allowed to access them. And VCL controls simply don't react well when those window handles get messed up when accessed across thread boundaries. Don't do it. That is a very bad design choice. Handle all of your UI needs in the default main UI thread only. You can use multiple worker threads to handle your business logic however you want, and you can create a separate TForm to associate with each worker thread if that is what you need. Just make sure that any data you share across threads is adequately protected from concurrent access, and that you have worker threads synchronize with the main UI thread whenever they need to access the UI.

Those are not valid Delphi declarations. Those are valid Delphi declarations (well, almost - Write() needs a semicolon instead of a comma between Buffer and Count). They work the same as they do in C++. Most likely, you are simply passing in the wrong values, so you end up reading/writing data from the wrong memory addresses. Hard to say since you did not show the code you are having trouble with. In Delphi, an untyped 'const'/`var' parameter is just a reference to a memory address, so you can pass in whatever variable you want and the compiler will pass in the memory address of that variable. In C++, the closest equivalent to that is a '(const) void*' pointer, using the '&' operator to get the address of a variable. So, in Delphi, to read/write data from/to an array, for instance, you would pass in the 1st element of the array, and the compiler will pass in the memory address of that element. On the other hand, if you have a pointer to memory, you would have to dereference the pointer so the parameter can receive the memory address of the thing being pointed at. Here is a few examples using different types of memory: var Value: Integer; ComPort.Read(Value, SizeOf(Value)); ComPort.Write(Value, SizeOf(Value)); var Buffer: array[0..255] of Byte; ComPort.Read(Buffer[0], SizeOf(Buffer)); // or: ComPort.Read(Buffer, SizeOf(Buffer)); ComPort.Write(Buffer[0], SizeOf(Buffer)); // or: ComPort.Write(Buffer, SizeOf(Buffer)); var Buffer: array of Byte; SetLength(Buffer, ...); ComPort.Read(Buffer[0], Length(Buffer)); // or: ComPort.Read(PByte(Buffer)^, Length(Buffer)); ComPort.Write(Buffer[0], Length(Buffer)); // or: ComPort.Write(PByte(Buffer)^, Length(Buffer)); var Str: AnsiString; SetLength(Str, ...); ComPort.Read(Str[0], Length(Str)); // or: ComPort.Read(PAnsiChar(Str)^, Length(Str)); ComPort.Write(Str[0], Length(Str)); // or: ComPort.Write(PAnsiChar(Str)^, Length(Str)); var UStr: UnicodeString; SetLength(UStr, ...); ComPort.Read(UStr[0], Length(UStr) * SizeOf(WideChar)); // or: ComPort.Read(PWideChar(Str)^, Length(UStr) * SizeOf(WideChar)); ComPort.Write(UStr[0], Length(UStr) * SizeOf(WideChar)); // or: ComPort.Write(PWideChar(Str)^, Length(UStr) * SizeOf(WideChar)); type PMyRec = ^TMyRec; TMyRec = record Value: Integer; ... end; var Ptr: PMyRec; NumBytes: Integer; NumBytes := SizeOf(TMyRec) * ...; GetMem(Ptr, NumBytes); ComPort.Read(Ptr^, NumBytes); ComPort.Write(Ptr^, NumBytes); FreeMem(Ptr); Those are compiler intrinsic functions, they have special handling for parameters that you don't normally get with user-defined functions.

Duplicate:

There is no link (not that it matters, I didn't ask for the code, I asked you to clarify your question). That doesn't clarify anything. My earlier question still stands.