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  • What is the difference between a constructor and a procedure in Delphi records?

    - by HMcG
    Is there difference in behavior between a constructor call and a procedure call in Delphi records? I have a D2010 code sample I want to convert to D2009 (which I am using). The sample uses a parameterless constructor, which is not permitted in Delphi 2009. If I substitute a simple parameterless procedure call, is there any functional difference for records? I.E. TVector = record private FImpl: IVector; public constructor Create; // not allowed in D2009 end; becomes TVector = record private FImpl: IVector; public procedure Create; // so change to procedure end; As far as I can see this should work, but I may be missing something.

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  • How to disable a warning in Delphi about "return value ... might be undefined"?

    - by Lasse V. Karlsen
    I have a function that gives me the following warning: [DCC Warning] filename.pas(6939): W1035 Return value of function 'function' might be undefined The function, however, is clean, small, and does have a known, expected, return value. The first statement in the function is: Result := ''; and there is no local variable or parameter called Result either. Is there any kind of pragma-like directive I can surround this method with to remove this warning? This is Delphi 2007. Unfortunately, the help system on this Delphi installation is shot, so I can't pop up the help for that warning right now. Anyone know off the top of their head what I can do?

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  • Need to allocate memory before a Delphi string copy?

    - by Duncan
    Do I need to allocate memory when performing a Delphi string copy? I've a function which posts a Windows message to another form in my application. It looks something like this: // Note: PThreadMessage = ^TThreadMessage; TThreadMessage = String; function PostMyMessage( aStr : string ); var gMsgPtr : PThreadMessage; gStrLen : Integer; begin New(gMsgPtr); gStrLen := StrLen(PWideChar(aMsg)); gMsgPtr^ := Copy(aMsg, 0, gStrLen); PostMessage(ParentHandle, WM_LOGFILE, aLevel, Integer(gMsgPtr)); // Prevent Delphi from freeing this memory before consumed. LParam(gMsgPtr) := 0; end;

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  • Bug in Delphi XE RegularExpressions Unit

    - by Jan Goyvaerts
    Using the new RegularExpressions unit in Delphi XE, you can iterate over all the matches that a regex finds in a string like this: procedure TForm1.Button1Click(Sender: TObject); var RegEx: TRegEx; Match: TMatch; begin RegEx := TRegex.Create('\w+'); Match := RegEx.Match('One two three four'); while Match.Success do begin Memo1.Lines.Add(Match.Value); Match := Match.NextMatch; end end; Or you could save yourself two lines of code by using the static TRegEx.Match call: procedure TForm1.Button2Click(Sender: TObject); var Match: TMatch; begin Match := TRegEx.Match('One two three four', '\w+'); while Match.Success do begin Memo1.Lines.Add(Match.Value); Match := Match.NextMatch; end end; Unfortunately, due to a bug in the RegularExpressions unit, the static call doesn’t work. Depending on your exact code, you may get fewer matches or blank matches than you should, or your application may crash with an access violation. The RegularExpressions unit defines TRegEx and TMatch as records. That way you don’t have to explicitly create and destroy them. Internally, TRegEx uses TPerlRegEx to do the heavy lifting. TPerlRegEx is a class that needs to be created and destroyed like any other class. If you look at the TRegEx source code, you’ll notice that it uses an interface to destroy the TPerlRegEx instance when TRegEx goes out of scope. Interfaces are reference counted in Delphi, making them usable for automatic memory management. The bug is that TMatch and TGroupCollection also need the TPerlRegEx instance to do their work. TRegEx passes its TPerlRegEx instance to TMatch and TGroupCollection, but it does not pass the instance of the interface that is responsible for destroying TPerlRegEx. This is not a problem in our first code sample. TRegEx stays in scope until we’re done with TMatch. The interface is destroyed when Button1Click exits. In the second code sample, the static TRegEx.Match call creates a local variable of type TRegEx. This local variable goes out of scope when TRegEx.Match returns. Thus the reference count on the interface reaches zero and TPerlRegEx is destroyed when TRegEx.Match returns. When we call MatchAgain the TMatch record tries to use a TPerlRegEx instance that has already been destroyed. To fix this bug, delete or rename the two RegularExpressions.dcu files and copy RegularExpressions.pas into your source code folder. Make these changes to both the TMatch and TGroupCollection records in this unit: Declare FNotifier: IInterface; in the private section. Add the parameter ANotifier: IInterface; to the Create constructor. Assign FNotifier := ANotifier; in the constructor’s implementation. You also need to add the ANotifier: IInterface; parameter to the TMatchCollection.Create constructor. Now try to compile some code that uses the RegularExpressions unit. The compiler will flag all calls to TMatch.Create, TGroupCollection.Create and TMatchCollection.Create. Fix them by adding the ANotifier or FNotifier parameter, depending on whether ARegEx or FRegEx is being passed. With these fixes, the TPerlRegEx instance won’t be destroyed until the last TRegEx, TMatch, or TGroupCollection that uses it goes out of scope or is used with a different regular expression.

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  • Switching Programming Languages

    - by no spoon
    Hi I'm a senior level Delphi developer looking for move into either C# or possibly Java roles. I have around 8 years of development experience of which pretty much all of it is in Delphi, I have very little commercial experience in C# and no commercial experience in Java. I have about 6 months worth of academic experience in both Java and C# from some University papers I took a 4 years ago and use these languages for hobby projects, so I know the languages I just don't have the commercial experience to back it up. Given that I'm too over qualified for a junior role but do not have the commercial experience for even an intermediate role how does one go about changing jobs?

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  • Delphi : nouvelle version disponible de JVCL, la bibliothèque open-source de composants visuels et non-visuels

    La version 3.46 de la JVCL est disponible L'équipe JVCL est fière d'annoncer la sortie de la version stable de la bibliothèque de composants JVCL version 3.46. La JVCL est une bibliothèque comprenant environ 600 composants visuels et non-visuels pour Delphi 6, 7, 2006, 2007, 2009, 2010, XE, XE2 et XE3; C++Builder 6, 2006, 2007, 2009, 2010, XE, XE2 et XE3. La JVCL est distribué sous licence Mozilla Public License Version 1.1, est entièrement gratuite pour toute utilisation (open source, shareware ou commerciale) et inclus le code source de tous les composants. Cette version apporte de nombreux correctifs et le support de la dernière v...

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  • Why does my Delphi program's memory continue to grow?

    - by lkessler
    I am using Delphi 2009 which has the FastMM4 memory manager built into it. My program reads in and processes a large dataset. All memory is freed correctly whenever I clear the dataset or exit the program. It has no memory leaks at all. Using the CurrentMemoryUsage routine given in spenwarr's answer to: http://stackoverflow.com/questions/437683/how-to-get-the-memory-used-by-a-delphi-program, I have displayed the memory used by FastMM4 during processing. What seems to be happening is that memory is use is growing after every process and release cycle. e.g.: 1,456 KB used after starting my program with no dataset. 218,455 KB used after loading a large dataset. 71,994 KB after clearing the dataset completely. If I exit at this point (or any point in my example), no memory leaks are reported. 271,905 KB used after loading the same dataset again. 125,443 KB after clearing the dataset completely. 325,519 KB used after loading the same dataset again. 179,059 KB after clearing the dataset completely. 378,752 KB used after loading the same dataset again. It seems that my program's memory use is growing by about 53,400 KB upon each load/clear cycle. Task Manager confirms that this is actually happening. I have heard that FastMM4 does not always release all of the program's memory back to the Operating system when objects are freed so that it can keep some memory around when it needs more. But this continual growing bothers me. Since no memory leaks are reported, I can't identify a problem. Does anyone know why this is happening, if it is bad, and if there is anything I can or should do about it?

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  • How to create an instance of object with RTTI in Delphi 2010?

    - by Paul
    As we all known, when we call a constructor of a class like this: instance := TSomeClass.Create; The Delphi compiler actually do the following things: Call the static NewInstance method to allocate memory and initialize the memory layout. Call the constructor method to perform the initialization of the class Call the AfterConstruction method It's simple and easy to understand. but I'm not very sure how the compiler handle exceptions in the second and the third step. It seems there are no explicit way to create an instance using a RTTI constructor method in D2010. so I wrote a simple function in the Spring Framework for Delphi to reproduce the process of the creation. class function TActivator.CreateInstance(instanceType: TRttiInstanceType; constructorMethod: TRttiMethod; const arguments: array of TValue): TObject; var classType: TClass; begin TArgument.CheckNotNull(instanceType, 'instanceType'); TArgument.CheckNotNull(constructorMethod, 'constructorMethod'); classType := instanceType.MetaclassType; Result := classType.NewInstance; try constructorMethod.Invoke(Result, arguments); except on Exception do begin if Result is TInterfacedObject then begin Dec(TInterfacedObjectHack(Result).FRefCount); end; Result.Free; raise; end; end; try Result.AfterConstruction; except on Exception do begin Result.Free; raise; end; end; end; I feel it maybe not 100% right. so please show me the way. Thanks!

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  • How to build the SysUtils.Format string function in Delphi?

    - by Sam
    If I have the following Delphi code type TFormatArgs = array of TVarRec; procedure DelphiGodsGiveMeTheAnswerPrettyPlease; var iMyAge: integer; iMyIQ: integer; sCode: string; sText: string; begin iMyAge := 5; iMyIQ := -5; sCode := 'Format(''My age is %d and my IQ is %d'', [iMyAge, iMyIQ])'; sText := FormatThis(sCode, iMyAge, iMyIQ); end; function FormatThis(sFormatCode: string; iVar1: integer; iVar2: integer): string; var sFormatString: string; arFormatArgs: TFormatArgs; begin sFormatString := GetFormatString(sFormatCode); // I can implement this function arFormatArgs := ConstructFormatArgs(iVar1, iVar2); // NEED HELP HERE! result := SysUtils.Format(sFormatString, arFormatArgs); end; How can I implement my ConstructFormatArgs function in Delphi (not Assembly)? I'm afraid the assembly code in SysUtils.WideFormatBuf is just a little bit beyond my comprehension skills! Any ideas? I'm seeking divine assistance. Even if you can contribute just a little hint here and there on how to improve it or help me progress with this exercise. TIA.

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  • Delphi - How do I split a string into an array of strings based on a delimiter?

    - by Ryan
    Hello all, I'm trying to find a Delphi function that will split an input string into an array of strings based on a delimiter. I've found a lot on Google, but all seem to have their own issues and I haven't been able to get any of them to work. I just need to split a string like: "word:doc,txt,docx" into an array based on ':'. The result would be ['word', 'doc,txt,docx']. Does anyone have a function that they know works? Thank you

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  • How do I use WMI with Delphi without drastically increasing the application's file size?

    - by Mick
    I am using Delphi 2010, and when I created a console application that prints "Hello World", it takes 111 kb. If I want to query WMI with Delphi, I add WBEMScripting_TLB, ActiveX, and Variants units to my project. If I perform a simple WMI query, my executable size jumps to 810 kb. I Is there anyway to query WMI without such a large addition to the size of the file? Forgive my ignorance, but why do I not have this issue with C++? Here is my code: program WMITest; {$APPTYPE CONSOLE} uses SysUtils, WBEMScripting_TLB, ActiveX, Variants; function GetWMIstring(wmiHost, root, wmiClass, wmiProperty: string): string; var Services: ISWbemServices; SObject: ISWbemObject; ObjSet: ISWbemObjectSet; SProp: ISWbemProperty; Enum: IEnumVariant; Value: Cardinal; TempObj: OLEVariant; loc: TSWbemLocator; SN: string; i: integer; begin Result := ''; i := 0; try loc := TSWbemLocator.Create(nil); Services := Loc.ConnectServer(wmiHost, root {'root\cimv2'}, '', '', '', '', 0, nil); ObjSet := Services.ExecQuery('SELECT * FROM ' + wmiClass, 'WQL', wbemFlagReturnImmediately and wbemFlagForwardOnly, nil); Enum := (ObjSet._NewEnum) as IEnumVariant; if not VarIsNull(Enum) then try while Enum.Next(1, TempObj, Value) = S_OK do begin try SObject := IUnknown(TempObj) as ISWBemObject; except SObject := nil; end; TempObj := Unassigned; if SObject <> nil then begin SProp := SObject.Properties_.Item(wmiProperty, 0); SN := SProp.Get_Value; if not VarIsNull(SN) then begin if varisarray(SN) then begin for i := vararraylowbound(SN, 1) to vararrayhighbound(SN, 1) do result := vartostr(SN[i]); end else Result := SN; Break; end; end; end; SProp := nil; except Result := ''; end else Result := ''; Enum := nil; Services := nil; ObjSet := nil; except on E: Exception do Result := e.message; end; end; begin try WriteLn('hello world'); WriteLn(GetWMIstring('.', 'root\CIMV2', 'Win32_OperatingSystem', 'Caption')); WriteLn('done'); except on E: Exception do Writeln(E.ClassName, ': ', E.Message); end; end.

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  • Is it possible to add "assert" as a keyword in Delphi?

    - by stanleyxu2005
    I write couple of "assert(...)" in code, to make sure that pre- and post-conditions should be satisfied. We can tell the Delphi compiler, whether to compile with assertions in a debug version and without assertions in a release version. I would like to know, if it is possible, to highlight "assert" like other Pascal keywords?

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  • What is a best free way to make form resizeable in Delphi 7?

    - by Tofig Hasanov
    I need my form in Delphi to be resizeable, and all components and controls should stretch proportionally, along with font sizes etc. Right now in order to resize components I write a code inside "OnResize" event, and manually calculate all components' sizes and fonts. I would like to have more simple solution, which I can apply to different applications without rewriting this code for each form. I found some components on the web, but they are shareware. Can you suggest something?

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  • Delphi LoadLibrary Failing to find DLL other directory - any good options?

    - by Chris Thornton
    Two Delphi programs need to load foo.dll, which contains some code that injects a client-auth certificate into a SOAP request. foo.dll resides in c:\fooapp\foo.dll and is normally loaded by c:\fooapp\foo.exe. That works fine. The other program needs the same functionality, but it resides in c:\program files\unwantedstepchild\sadapp.exe. Both aps load the DLL with this code: FOOLib := LoadLibrary('foo.dll'); ... If FOOLib <> 0 then begin FOOProc := GetProcAddress(FOOLib , 'xInjectCert'); FOOProc(myHttpRequest, Data, CertName); end; It works great for foo.exe, as the dll is right there. sadapp.exe fails to load the library, so FOOLib is 0, and the rest never gets called. The sadapp.exe program therefore silently fails to inject the cert, and when we test against production, it the cert is missing, do the connection fails. Obviously, we should have fully-qualified the path to the DLL. Without going into a lot of details, there were aspects of the testing that masked this problem until recently, and now it's basically too late to fix in code, as that would require a full regression test, and there isn't time for that. Since we've painted ourselves into a corner, I need to know if there are any options that I've overlooked. While we can't change the code (for this release), we CAN tweak the installer. I've found that placing c:\fooapp into the path works. As does adding a second copy of foo.dll directly into c:\program files\unwantedstepchild. c:\fooapp\foo.exe will always be running while sadapp.exe is running, so I was hoping that Windows would find it that way, but apparently not. Is there a way to tell Windows that I really want that same DLL? Maybe a manifest or something? This is the sort of "magic bullet" that I'm looking for. I know I can: Modify the windows path, probably in the installer. That's ugly. Add a second copy of the DLL, directly into the unwantedstepchild folder. Also ugly Delay the project while we code and test a proper fix. Unacceptable. Other? Thanks for any guidance, especially with "Other". I understand that this issue is not necessarily specific to Delphi. Thanks!

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  • What is the Fastest Way to Check for a Keyword in a List of Keywords in Delphi?

    - by lkessler
    I have a small list of keywords. What I'd really like to do is akin to: case MyKeyword of 'CHIL': (code for CHIL); 'HUSB': (code for HUSB); 'WIFE': (code for WIFE); 'SEX': (code for SEX); else (code for everything else); end; Unfortunately the CASE statement can't be used like that for strings. I could use the straight IF THEN ELSE IF construct, e.g.: if MyKeyword = 'CHIL' then (code for CHIL) else if MyKeyword = 'HUSB' then (code for HUSB) else if MyKeyword = 'WIFE' then (code for WIFE) else if MyKeyword = 'SEX' then (code for SEX) else (code for everything else); but I've heard this is relatively inefficient. What I had been doing instead is: P := pos(' ' + MyKeyword + ' ', ' CHIL HUSB WIFE SEX '); case P of 1: (code for CHIL); 6: (code for HUSB); 11: (code for WIFE); 17: (code for SEX); else (code for everything else); end; This, of course is not the best programming style, but it works fine for me and up to now didn't make a difference. So what is the best way to rewrite this in Delphi so that it is both simple, understandable but also fast? (For reference, I am using Delphi 2009 with Unicode strings.) Followup: Toby recommended I simply use the If Then Else construct. Looking back at my examples that used a CASE statement, I can see how that is a viable answer. Unfortunately, my inclusion of the CASE inadvertently hid my real question. I actually don't care which keyword it is. That is just a bonus if the particular method can identify it like the POS method can. What I need is to know whether or not the keyword is in the set of keywords. So really I want to know if there is anything better than: if pos(' ' + MyKeyword + ' ', ' CHIL HUSB WIFE SEX ') > 0 then The If Then Else equivalent does not seem better in this case being: if (MyKeyword = 'CHIL') or (MyKeyword = 'HUSB') or (MyKeyword = 'WIFE') or (MyKeyword = 'SEX') then In Barry's comment to Kornel's question, he mentions the TDictionary Generic. I've not yet picked up on the new Generic collections and it looks like I should delve into them. My question here would be whether they are built for efficiency and how would using TDictionary compare in looks and in speed to the above two lines? In later profiling, I have found that the concatenation of strings as in: (' ' + MyKeyword + ' ') is VERY expensive time-wise and should be avoided whenever possible. Almost any other solution is better than doing this.

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  • Delphi - Why does ExplicitWidth and ExplicitHeight keep appearing in .DFM files and what is it!?

    - by Pauk
    We've noticed that when checking in updates that our .DFM files have had ExplicitWidth and ExplicitHeight properties added for what appears to be no particular reason. My two questions are, what are they for and why do they get automatically added by Delphi? Below is an example with the property in: object Splitter2: TcxSplitter Left = 0 Top = 292 Width = 566 Height = 8 Cursor = crVSplit HotZoneClassName = 'TcxXPTaskBarStyle' AlignSplitter = salBottom Control = BottomPanel Color = clBtnFace ExplicitWidth = 8 end

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