Here are my types and variables, which are the same for both examples.

type
  TMyEnum = (my1, my2, my3, my4);

var
  myEnum: TMyEnum;
  val: Char;

Here are the two examples, side by side, with assembly code to follow.  BTW, compiler optimization was turned on.

  myEnum := my1;
  case myEnum of
    my1: val := '1';
    my2: val := '2';
    my3: val := '3';
    my4: val := '4';
  else
    val := '?';
  end;

  myEnum := my1;
  case myEnum of
    my3: val := '3';
    my1: val := '1';
    my4: val := '4';
    my2: val := '2';
  else
    val := '?';
  end;

Same number of lines of assembly code. There may be some internal CPU optimization, but I don’t expect there is any.

Conclusion: Order of the enum in the case statement does not change performance.  Anyone else have any details I missed, or evidence to the contrary?  I guess the next step is to test it in .NET and IL. . . .

As a note, you do not need to deploy any of these files, or the files in the SDK with your application. You just need to ensure that the Background Transfer Service is running on the target machine.

For more information, I have created a hub page on Advanced Downloads with Delphi that I will update with more information as I gather it.

Enjoy!

[Download C, TBL, H, PAS archive]

Technorati Tags: BITS, Downloads, Service, SDK, Library, Delphi programming

uses psAPI;
{...}
function CurrentProcessMemory: Cardinal;
var
  MemCounters: TProcessMemoryCounters;
begin
  MemCounters.cb := SizeOf(MemCounters);
  if GetProcessMemoryInfo(GetCurrentProcess,
      @MemCounters,
      SizeOf(MemCounters)) then
    Result := MemCounters.WorkingSetSize
  else
    RaiseLastOSError;
end;

Update: Thanks to Andreas for a heap free (no GetMem / FreeMem) method of doing this (via his comment!)

Not sure where I got the basics of this, but I added some better error handling to it and made it a function. WorkingSetSize is the amount of memory currently used. You can use similar code to get other values for the current process (or any process). You will need to include psAPI in your uses statement.

The PROCESS_MEMORY_COUNTERS record includes:

• PageFaultCount
• PeakWorkingSetSize
• WorkingSetSize
• QuotaPeakPagedPoolUsage
• QuotaPagedPoolUsage
• QuotaPeakNonPagedPoolUsage
• QuotaNonPagedPoolUsage
• PagefileUsage
• PeakPagefileUsage

You can find all of these values in Task Manager or Process Explorer.

Maybe this would be a good task for one of Delphi’s new records that include methods. . . .

It would appear

This has long been one of the strengths of Delphi – the strong collection of 3rd party components. 3rd party component development was of course fostered by the fact that Delphi came with full source for the VCL and RTL. A move the Microsoft if finally duplicating in releasing the source for the .NET framework. Although unlike Delphi, Microsoft will not allow you to modify and recompile the framework in your applications. With Delphi you can tweak the VCL and recompile it (not a trivial task, but allowable and possible) for your applications. Granted doing so makes moving to new versions of Delphi a little more tricky, and you cannot redistribute the modified source.

BTW, notice the link to my TurboPower page on line 27.

• Exceptional Exceptions
• Implementing Cryptography
• Class Helpers: Friend or Foe
• Delphi Robot Rage

They all went really well I thought. Unfortunately I pushed the deadline back too far on Delphi Robot Rage and my JIT Presentation didn’t happen on time. Sorry to everyone about that.

Check back often for updates (seriously), or let me know if I missed something you are looking for from my sessions.

Thanks!

Well it turns out that if you want to be Microsoft Windows Vista Logo certified, then you need to crash your application on certain exceptions.

Applications must handle only exceptions that are known and expected, and Windows Error Reporting must not be disabled. If a fault (such as an Access Violation) is injected into an application, the application must allow Windows Error Reporting to report this crash. (from requirement 3.2 Resilient Software: Eliminate Application Failures)

Microsoft’s rational for this requirement is the ISV will receive the error report Microsoft collects for them. I guess most software developers don’t have access to tools like we do in Delphi to catch exceptions and log them for us.

So short of tossing out the Forms unit and writing everything from scratch, how can you get around the usefulness of the global exception handler.

My first thought was to create a custome application exception handler by placing a TApplicationEvents on your main form and assigning the OnException event. In the event include the line

  raise e;

This will pass an exception up to the operating system and terminate your application, at least when I tested it in Delphi 2007. When I tried it in Delphi 7, it didn’t work right.

A more elegant and involved solution:

First you need a couple global variables:

var
  GlobalExcept: Exception;
  GlobalExceptAddr: Pointer;

And a global exception handler:

procedure TForm1.ApplicationException(Sender: TObject; E: Exception);
begin
  if E is EAccessViolation then
  begin
    // Keep the exception object from being destroyed!
    AcquireExceptionObject;
    GlobalExcept := e;
    GlobalExceptAddr := ExceptAddr;
    Application.Terminate;
  end;
end;

The rest of the magic happens in the project file (DPR)

begin
  GlobalExcept := nil;
  GlobalExceptAddr := nil;
  try
    Application.Initialize;
    Application.CreateForm(TForm1, Form1);
  Application.Run;
  finally
    if Assigned( GlobalExcept ) then
    begin
      raise GlobalExcept at GlobalExceptAddr;
    end;
  end;
end.

And you can [download the code].

Thanks to Jeremi Reda for asking this question in borland.public.delphi.non-technical.

I didn’t cover this in my CodeRage II session on Exceptional Exceptions, but there is a lot of other cool stuff, like AcquireExceptionObject!

Requirements:

1. Robot must have unsecured source (no password, or password must be provided), although the source will not be revealed until after the challenge is completed.
2. If a unique skin is not used for your robot, then a new skin may be assigned to your robot for visual identification.
3. Competition is open to everyone. No purchase necessary. Not required to be in attendance at CodeRage II to enter or win, although that is the best way to see the action!
4. Email your robot to me (delphirobotrage@davinciunltd.com), and I will reply with acknowledgment. If I don’t reply, I didn’t receive it.

Deadline for submissions: November 26th, 2007 – midnight Pacific Time

Notice: There is an incompatibility between D-Robots and some video drivers (maybe just ATI). No known work around. It does work in a virtual machine, but your frame rate will be very poor.

If you submit your robot early enough, you might get some feedback from a practice round.

Short intro video online & Partial list of prizes.

Questions? Comments?

Now to figure out if the server can get the information it needs from itself without going through a socket connection to itself.  I can see that being a bad scenario if it keeps opening new sockets back to itself again. . . .

Almost as much  fun as leaving comments and ping backs on your own blog.

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