Anders Melander

3 hours ago, david berneda said:

https://engineertips.wordpress.com/2021/11/27/delphi-resize-jpeg/

StretchDraw? That's a horrible solution - to a 4 year old problem.

I would argue that the type of Epsilon depends on the use case; For one an absolute explicit Epsilon is suitable (SameValue(Value, Epsilon)), for another an absolute implicit Epsilon will make sense (SameValue(Value) but with some better defaults), and for yet another a relative magnitude Epsilon would be desirable (let's call it KasObSameValue(Value, Epsilon) since we don't have it in the RTL).

FWIW, the same discussion could be had about IsZero. I mostly use it to avoid division by zero and overflow errors caused by division by a very small number. I'm not really comfortable doing it but the alternative is the gazillion sporadic exceptions we had in the old application I'm working on, before we began using it.

Google "manifest cache"

1 minute ago, Kas Ob. said:

its documentation should declare it use low(reduced) precision for comparison by default.

No argument there.

33 minutes ago, Kas Ob. said:

The right way ...

I think you are missing my point.

I'm saying that SameValue, with Epsilon specified, is documented to work in the way it does now. If it didn't then that would be a bug.

You can argue that it would be better if it worked in another way (e.g. Epsilon relative to the magnitude of value) but that is not how it is documented to work, it is also subjective, and it depends on how one intends to use it.

It's like arguing that the right way to index strings is zero based.

5 minutes ago, Kas Ob. said:

the formula for the comparison should be

Should? As far as I can tell the current implementation matches the documented behavior. Yours doesn't.

You might prefer another behavior, which is perfectly reasonable, but it doesn't make the current one wrong.

I agree that SameValue without the Epsilon parameter is at best problematic but, with regard to the choice of default Epsilon, we don't know what the criteria was for the values they chose (because it isn't documented) so I can't see how we can say that they are wrong. Again; We might prefer other values but that doesn't make the current values wrong.

40 minutes ago, Kas Ob. said:

SameValue will murder some of them as its error tolerance is fixed

Only if you don't specify a tolerance.

I can't see anything wrong with it if you specify a tolerance.

Multiply by a 10^"number of decimals", Trunc to convert to integer, Assert on the integer value

As far as I can tell they've been forced to replace their proprietary APIs with standard APIs (in order to avoid vendor lock-in) and to allow competing third party applications access to their map data. Did I understand that right?

It seems Google has few friends in the map business; They aren't allowed to link to Google Maps from their Google search results - or even from the search page (which is pretty stupid and doesn't do the users any good), while the same restrictions doesn't apply to Bing. Could it be that Bing map data is provided by Tom-Tom?

5 hours ago, bk31415 said:

I am writing an (MQTT) broker (serves) that serves about 100 clients.

9 minutes ago, bk31415 said:

Both machines (A and B) single-user, they will access one another over the local network --not from Internet or similar.

Alright then.

So you are going to violate the license and don't want that aspect discussed. That's between you, Microsoft, and whatever unfortunate user/client, if any, this involves but maybe you shouldn't ask us to help you do it.

1 minute ago, bk31415 said:

Second part applies.

You mean you are "installing the software on a device for use only by remote users"?

2 minutes ago, bk31415 said:

This must be the strictest possible interpretation out there.

No it's not; You are not allowed to use a desktop Windows as a server. What other people that violate the license say about that isn't really relevant.

Quote

Installation and Use Rights.

Restrictions.

For the avoidance of doubt, this license does not give you any right to, and you may
not (and you may not permit any other person or entity to):

...

use the software as server software or to operate the device as a server, except as permitted under Section 2(d)(iii) below; use the software to offer commercial hosting services; make the software available for simultaneous use by more than one user over a network, except as permitted under Section 2(d)(vi) below;
install the software on a server for remote access or use over a network; or install the software on a device for use only by remote users;

Just now, Attila Kovacs said:

if you're turning the machine into a server that violates terms intended for client/desktop use 

Exactly.

Read the EULA. Search for "server". It's stated pretty clearly what you can and cannot do.

Then I think you need to familiarize yourself with the Windows EULA.

So this is a hobby project. Right?

3 hours ago, bk31415 said:

But, I'd like the machine this thing runs on to have a live backup machine. I.e. an identical machine that takes over in case the master fails.

 

IOW, a High Availability situation.

IOW, a failover cluster.

Have you considered a Windows Workgroup cluster? I believe they can be built fairly cheap.

FWIW, madExcept didn't find any memory overwrites but of course caught the exception:

exception class    : EAccessViolation
exception message  : Access violation at address 58C66418 in module 'COMCTL32.dll'. Read of address 0000000C.

main thread ($3be0):
58c66418 +000 COMCTL32.dll
74a25d96 +016 USER32.dll                             CallWindowProcW
00eb193d +131 Editor.exe   Vcl.Controls   11199  +34 TWinControl.DefaultHandler
00eb246a +01a Editor.exe   Vcl.Controls   11505   +1 TWinControl.WMCommand
00eac1b2 +2be Editor.exe   Vcl.Controls    7920  +91 TControl.WndProc
00eb17e7 +6a7 Editor.exe   Vcl.Controls   11154 +178 TWinControl.WndProc
00ece57f +23f Editor.exe   Vcl.StdCtrls    4849  +95 TCustomCombo.WndProc
00ed02e4 +1f0 Editor.exe   Vcl.StdCtrls    5642  +42 TCustomComboBox.WndProc
00e2f31c +014 Editor.exe   System.Classes 19084   +8 StdWndProc
00eb0cac +02c Editor.exe   Vcl.Controls   10823   +3 TWinControl.MainWndProc
00e2f31c +014 Editor.exe   System.Classes 19084   +8 StdWndProc
74a260b8 +048 USER32.dll                             SendMessageW
74a25d96 +016 USER32.dll                             CallWindowProcW
00ed7310 +2bc Editor.exe   Vcl.StdCtrls   11307  +70 TComboBoxStyleHook.ListBoxWndProc
00e2f31c +014 Editor.exe   System.Classes 19084   +8 StdWndProc
74a2620b +00b USER32.dll                             DispatchMessageW
00f760bb +0f3 Editor.exe   Vcl.Forms      13282  +23 TApplication.ProcessMessage
00f760fe +00a Editor.exe   Vcl.Forms      13312   +1 TApplication.HandleMessage
00f7643d +0d1 Editor.exe   Vcl.Forms      13451  +27 TApplication.Run
00ff37a6 +05a Editor.exe   Editor            21   +5 initialization
75f7fcc7 +017 KERNEL32.DLL                           BaseThreadInitThunk

13 hours ago, FmxToPdf said:

create professional looking PDFs from your mobile app!

Isn't that stretching the meaning of mobile quite a bit - literally?

I mean the UI looks like that of a regular desktop application. Never mind why, but how would you operate this on a phone?

My guess is that something you are doing elsewhere is corrupting memory and what you are seeing are just secondary errors.

You can probably use madExcept, with memory overrun check enabled, to find the origin of the problem.

There are no rules against necro-posting; It's just pointless.

SHChangeNotify got me thinking...

Assuming a call to SHChangeNotify(SHCNE_ASSOCCHANGED) is all that is needed to rebuild the cache, is there something in Windows that we know makes that call? A quick search of "the source" gave the answer: The assoc command of the Windows shell; All it does is write an entry to the registry and then make the SHChangeNotify call.

assoc .foobar=text

Voila!

If you want to remove the file association entry again then it's just:

assoc .foobar=

Admin privs required, btw.

I used to be able to reset the cache without a reboot with:

ie4uinit.exe -ClearIconCache

or

ie4uinit.exe -show

but I haven't had much success with those methods lately.

It definitely is possible to clear the cache without a reboot or killing explorer but it seems Microsoft doesn't want to make it easy for us.
See: SHChangeNotify

If you mean to expose the TModel record from the TModels list encapsulation then you can do so by (also) exposing record pointers:

type
  TModel = record
    Foo: string;
    Bar: integer;
  end;

  PModel = ^TModel;

  TModels = class
  private
    FItems: TList<TModel>;
  private
    function GetModel(Index: integer): TModel;
    procedure SetModel(Index: integer; const Value: TModel);
    function GetData(Index: integer): PModel;
  public
    property Items[Index: integer]: TModel read GetModel write SetModel; default;
    property Data[Index: integer]: PModel read GetData;
  end;
      
function TModels.GetModel(Index: integer): TModel;
begin
  Result := FItems[Index];
end;

procedure TModels.SetModel(Index: integer; const Value: TModel);
begin
  FItems[Index] := Value;
end;

function TModels.GetData(Index: integer): PModel;
begin
  Result := @FItems[Index];
end;

var Models: TModels;
var Model: TModel;
...
Model := Models[0];
...
Models[0] := Model;
...
Models.Data[0].Foo := 'Hello world';
Models.Data[0].Bar := 42;

7 minutes ago, Squall_FF8 said:

When I try to compile I get error: [dcc32 Error]  E2064 Left side cannot be assigned to

Why I get this error?

Because the TList<T>.Items property getter returns a read-only copy of the record. This is the same for all properties that return a record.

You can use the TList<T>.List property to gain access to the internal array of TList<T>.

24 minutes ago, David Heffernan said:

It's pretty rare for absolute to be useful. Pretend it doesn't exists, and you'll get a long way. 

I agree - but here's a few examples of where I've used it:

// Using absolute to rename a public API function while maintaining backward compatibility:
// - MyFunction is the old API entrypoint.
// - NewNameSameFunction is the new API entrypoint.
type
  TMyDelegate = procedure(X, Y, Z: Single);

var
  NewNameSameFunction: TMyDelegate

var
  MyFunction: TMyDelegate absolute NewNameSameFunction deprecated 'Use NewNameSameFunction instead';

// Same with global vars:
type
  TLUT88 = array[byte, byte] of byte;
  
var
  DivMul255Table: TLUT88;
  MulDiv255Table: TLUT88;

var
  RcTable: TLUT88 absolute DivMul255Table;
  DivTable: TLUT88 absolute MulDiv255Table;

// Casting between "uncastable" types without pointers
procedure FooBar(const X1, Y1, X2, Y2: Single)
var
  Y1bin: Cardinal absolute Y1;
  Y2bin: Cardinal absolute Y2;
begin
  // Fast way of testing if a Single is zero; Same as "if (Y1 = 0) and (Y2 = 0) then" but faster.
  if (Y1bin shl 1 = 0) and (Y2bin shl 1 = 0) then
    Exit;
  ...
end;