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• Ho to convert classname as string to a class ?

  - by Roland Bengtsson

  I have classnames in a stringlist. For example it could be 'TPlanEvent', 'TParcel', 'TCountry' etc. Now I want to find out the sizes by looping the list. It works to have: Size := TCountry.InstanceSize; But I want it like this: for i := 0 to ClassList.Count - 1 do Size := StringToClass(ClassList[i]).InstanceSize; Obviously my question is what to write instead of method StringToClass to convert the string to a class.

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• Components for creating Archives

  - by John

  Hello, I'm searching for a simple,free component for creating archives with the capability of adding files to an already existing archive.Compressions is not a matter as much as performance so even "store" will be useful. Please help me find one.

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• How to execute a program on PostBuild event in parallel?

  - by John

  I managed to set the compiler to execute another program when the project is built/ran with the following directive in project options: call program.exe param1 param2 The problem is that the compiler executes "program.exe" and waits for it to terminate and THEN the project executable is ran. What I ask: How to set the compiler to run both executables in paralel without waiting for the one in PostBuild event to terminate? Thanks in advance

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• Lock-Free, Wait-Free and Wait-freedom algorithms for non-blocking multi-thread synchronization.

  - by GJ

  In multi thread programming we can find different terms for data transfer synchronization between two or more threads/tasks. When exactly we can say that some algorithem is: 1)Lock-Free 2)Wait-Free 3)Wait-Freedom I understand what means Lock-free but when we can say that some synchronization algorithm is Wait-Free or Wait-Freedom? I have made some code (ring buffer) for multi-thread synchronization and it use Lock-Free methods but: 1) Algorithm predicts maximum execution time of this routine. 2) Therad which call this routine at beginning set unique reference, what mean that is inside of this routine. 3) Other threads which are calling the same routine check this reference and if is set than count the CPU tick count (measure time) of first involved thread. If that time is to long interrupt the current work of involved thread and overrides him job. 4) Thread which not finished job because was interrupted from task scheduler (is reposed) at the end check the reference if not belongs to him repeat the job again. So this algorithm is not really Lock-free but there is no memory lock in use, and other involved threads can wait (or not) certain time before overide the job of reposed thread. Added RingBuffer.InsertLeft function: function TgjRingBuffer.InsertLeft(const link: pointer): integer; var AtStartReference: cardinal; CPUTimeStamp : int64; CurrentLeft : pointer; CurrentReference: cardinal; NewLeft : PReferencedPtr; Reference : cardinal; label TryAgain; begin Reference := GetThreadId + 1; //Reference.bit0 := 1 with rbRingBuffer^ do begin TryAgain: //Set Left.Reference with respect to all other cores :) CPUTimeStamp := GetCPUTimeStamp + LoopTicks; AtStartReference := Left.Reference OR 1; //Reference.bit0 := 1 repeat CurrentReference := Left.Reference; until (CurrentReference AND 1 = 0)or (GetCPUTimeStamp - CPUTimeStamp > 0); //No threads present in ring buffer or current thread timeout if ((CurrentReference AND 1 <> 0) and (AtStartReference <> CurrentReference)) or not CAS32(CurrentReference, Reference, Left.Reference) then goto TryAgain; //Calculate RingBuffer NewLeft address CurrentLeft := Left.Link; NewLeft := pointer(cardinal(CurrentLeft) - SizeOf(TReferencedPtr)); if cardinal(NewLeft) < cardinal(@Buffer) then NewLeft := EndBuffer; //Calcolate distance result := integer(Right.Link) - Integer(NewLeft); //Check buffer full if result = 0 then //Clear Reference if task still own reference if CAS32(Reference, 0, Left.Reference) then Exit else goto TryAgain; //Set NewLeft.Reference NewLeft^.Reference := Reference; SFence; //Try to set link and try to exchange NewLeft and clear Reference if task own reference if (Reference <> Left.Reference) or not CAS64(NewLeft^.Link, Reference, link, Reference, NewLeft^) or not CAS64(CurrentLeft, Reference, NewLeft, 0, Left) then goto TryAgain; //Calcolate result if result < 0 then result := Length - integer(cardinal(not Result) div SizeOf(TReferencedPtr)) else result := cardinal(result) div SizeOf(TReferencedPtr); end; //with end; { TgjRingBuffer.InsertLeft } RingBuffer unit you can find here: RingBuffer, CAS functions: FockFreePrimitives, and test program: RingBufferFlowTest Thanks in advance, GJ

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• How to get/create anonymous method from TRttiMethod?

  - by Heinrich Ulbricht

  I want to handle a TRttiMethod as anonymous method. How could I do this? Here is a simplified example of how I wish things to work: Interface: TMyClass = class public // this method will be acquired via Rtti procedure Foo; // this method shall return above Foo as anonymous method function GetMethodAsAnonymous: TProc; end; Implementation: function TMyClass.GetMethodAsAnonymous: TProc; var Ctx: TRttiContext; RttiType: TRttiType; RttiMethod: TRttiMethod; begin Ctx := TRttiContext.Create; try RttiType := Ctx.GetType(Self.ClassType); RttiMethod := RttiType.GetMethod('Foo'); Result := ??????; // <-- I want to put RttiMethod here - but how? finally Ctx.Free; end; end;

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• How retrive full path with file name or folder name from ShellTreeView/ShellListView

  - by Dev

  Sir, I create a project, where I use ShellTreeView, ShellListView, ListView. Now I drag folder from ShellTreeView and files from ShellListView. Now I want to retrieve file name including full path (like: c:\abc\file.txt) or folder (like C:\abc). For retrieving the path I use a command button and a text box. What will the code? Dev

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• How to show scrollbars in TScrollBox after it has been made visible again?

  - by aleluja

  Hi, I've ran into one small problem. I am dynamicaly generating some controls and place them on a TScrollbox component. But i noticed that if scrollbox is visible, user can clearly see each of the controls being created and placed. So it looksl ike lots of work is being done and it is slow. I hid the scrollbox and generated all the controls on it, which took much less time and no flickering and alike. But here's the problem. When i unhide the scrollbox, its' scrollbar doesn't appear untill i actually resize the form. (The alignment of scrollbox is alClient) Any ideas on how to fix this? Tried repainting, but it didn't work. Refresh didn't work either. Thank you

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• How to make this OO?

  - by John

  Hello, Sorry for the poor title,I'm new to OOP so I don't know what is the term for what I need to do. I have, say, 10 different Objects that inherit one Object.They have different amount and type of class members,but all of them have one property in common - Visible. type TObj1=class(TObject) private a:integer; ...(More members) Visible:Boolean; end; TObj2=class(TObject) private b:String; ...(More members) Visible:Boolean; end; ...(Other 8 objects) For each of them I have a variable. var Obj1:TObj1; Obj2:TObj2; Obj3:TObj3; ....(Other 7 objects) Rule 1: Only one object can be initialized at a time(others have to be freed) to be visible. For this rule I have a global variable var CurrentVisibleObj:TObject; //Because they all inherit TObject Finally there is a procedure that changes visibility. procedure ChangeObjVisibility(newObj:TObject); begin CurrentVisibleObj.Free; //Free the old object CurrentVisibleObj:=newObj; //assign the new object CurrentVisibleObj:= ??? //Create new object CurrentVisibleObj.Visible:=true; //Set visibility to new object end; There is my problem,I don't know how to initialize it,because the derived class is unknown. How do I do this? I simplified the explanation,in the project there are TFrames each having different controls and I have to set visible/not visible the same way(By leaving only one frame initialized). Sorry again for the title,I'm very new to OOP.

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• Passing an Object as an Interface

  - by Christopher Chase

  This should be a simple answer, i believe its going to be a no, but taken from a larger project, i have an interface and the procedure iMyUnknown= interface(IInterface) ['..GUID..'] end; procedure WorkObject(iObj :iMyUnknown); i know this works var MyUnknown : iMyUnknown; begin if supports(obj, iMyUnknown, MyUnknown) then WorkObject(MyUnknown); But is it possible to do something like this? if supports(obj, iMyUnknown) then WorkObject(obj as iMyUnknown);

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• How to send windows messages to non-main forms

  - by Chris

  How do I go about sending a Windows Message to a form in my application that is not the MainForm? Using the code below gives me an Access Violation. procedure TMainForm.SendMessageToAnotherForm; begin SendMessage(MyForm.Handle,WM_MY_MESSAGE,0,0); end; MyForm has already been created and is the top most window.

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• Repeating procedure for every item in class

  - by Hendriksen123

  Data.XX.NewValue := Data.XX.SavedValue; Data.XX.OldValue := Data.XX.SavedValue; I need to do the above a large number of times, where XX represents the value in the class. Pretending there were 3 items in the list: Tim, Bob, Steve. Is there any way to do the above for all three people without typing out the above code three times? (Data is a class containing a number of Objects, each type TList, which contain OldValue, NewValue and SavedValue)

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• How sort a QuantumGrid on data from a different column

  - by norgepaul

  Is there a way to sort Devexpress QuantumGrid rows on data from a different column other than the one whose header has been clicked? For example, when the header of column A is clicked the rows of the grid are sorted on the data from column B. Visually it should still appear that it is column A that has been sorted as the sort glyphys will be shown in column A's header.

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• How to show the elapsed time while a long SQL Query is executed?

  - by Salvador

  i need to show a popup window before the a query execution, show the time elapsed while the sql query is executed , and close that windows when the query ends. actually i do something like this var frm : tFrmPopupElapsed; // this form have a ttimer and a tlabel to show the elapsed time //but the tlabel is not updated, i tried using update; and refresh; but nothing happens //the timer is enabled. begin frm:=tform.create(nil); frm.Init;//this procedure set the timer to enabled:=true try frm.Show(); ExecuteMyVeryLongQuery(); finally frm.Close; end; end; wich is the best way using a ttimer? a Tthread ? thanks in advance.

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• How to sort a QuantumGrid on data from a different column

  - by norgepaul

  Is there a way to sort Devexpress QuantumGrid rows on data from a different column other than the one whose header has been clicked? For example, when the header of column A is clicked the rows of the grid are sorted on the data from column B. Visually it should still appear that it is column A that has been sorted as the sort glyphys will be shown in column A's header.

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• Anyone know how to use TValue.AsType<TNotifyEvent> properly?

  - by Mason Wheeler

  I'm trying to use RTTI to add an event handler to a control, that may already have an event handler set. The code looks something like this: var prop: TRttiProperty; val: TValue; begin prop := FContext.GetType(MyControl.ClassInfo).GetProperty('OnChange'); val := prop.GetValue(MyControl); FOldOnChange := val.AsType<TNotifyEvent>; prop.SetValue(MyControl, TValue.From<TNotifyEvent>(self.MyOnChange)); end; I want this so I can do this in MyOnChange: begin if assigned(FOldOnChange) then FOldOnChange(Sender); //additional code here end; Unfortunately, the compiler doesn't seem to like the line FOldOnChange := val.AsType<TNotifyEvent>;. It says E2010 Incompatible types: 'procedure, untyped pointer or untyped parameter' and 'TNotifyEvent' Anyone know why that is or how to fix it? It looks right to me...

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• Is there a way to programmatically tell if particular block of memory was not freed by FastMM?

  - by Wodzu

  I am trying to detect if a block of memory was not freed. Of course, the manager tells me that by dialog box or log file, but what if I would like to store results in a database? For example I would like to have in a database table a names of routines which allocated given blocks. After reading a documentation of FastMM I know that since version 4.98 we have a possibility to be notified by manager about memory allocations, frees and reallocations as they occur. For example OnDebugFreeMemFinish event is passing to us a PFullDebugBlockHeader which contains useful informations. There is one thing that PFullDebugBlockHeader is missing - the information if the given block was freed by the application. Unless OnDebugFreeMemFinish is called only for not freed blocks? This is which I do not know and would like to find out. The problem is that even hooking into OnDebugFreeMemFinish event I was unable to find out if the block was freed or not. Here is an example: program MemLeakTest; {$APPTYPE CONSOLE} uses FastMM4, ExceptionLog, SysUtils; procedure MemFreeEvent(APHeaderFreedBlock: PFullDebugBlockHeader; AResult: Integer); begin //This is executed at the end, but how should I know that this block should be freed //by application? Unless this is executed ONLY for not freed blocks. end; procedure Leak; var MyObject: TObject; begin MyObject := TObject.Create; end; begin OnDebugFreeMemFinish := MemFreeEvent; Leak; end. What I am missing is the callback like: procedure OnMemoryLeak(APointer: PFullDebugBlockHeader); After browsing the source of FastMM I saw that there is a procedure: procedure LogMemoryLeakOrAllocatedBlock(APointer: PFullDebugBlockHeader; IsALeak: Boolean); which could be overriden, but maybe there is an easier way?

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• Strange behavior of move with strings

  - by Umair Ahmed

  I am testing some enhanced string related functions with which I am trying to use move as a way to copy strings around for faster, more efficient use without delving into pointers. While testing a function for making a delimited string from a TStringList, I encountered a strange issue. The compiler referenced the bytes contained through the index when it was empty and when a string was added to it through move, index referenced the characters contained. Here is a small downsized barebone code sample:- unit UI; interface uses System.SysUtils, System.Types, System.UITypes, System.Rtti, System.Classes, System.Variants, FMX.Types, FMX.Controls, FMX.Forms, FMX.Dialogs, FMX.Layouts, FMX.Memo; type TForm1 = class(TForm) Results: TMemo; procedure FormCreate(Sender: TObject); end; var Form1: TForm1; implementation {$R *.fmx} function StringListToDelimitedString ( const AStringList: TStringList; const ADelimiter: String ): String; var Str : String; Temp1 : NativeInt; Temp2 : NativeInt; DelimiterSize : Byte; begin Result := ' '; Temp1 := 0; DelimiterSize := Length ( ADelimiter ) * 2; for Str in AStringList do Temp1 := Temp1 + Length ( Str ); SetLength ( Result, Temp1 ); Temp1 := 1; for Str in AStringList do begin Temp2 := Length ( Str ) * 2; // Here Index references bytes in Result Move ( Str [1], Result [Temp1], Temp2 ); // From here the index seems to address characters instead of bytes in Result Temp1 := Temp1 + Temp2; Move ( ADelimiter [1], Result [Temp1], DelimiterSize ); Temp1 := Temp1 + DelimiterSize; end; end; procedure TForm1.FormCreate(Sender: TObject); var StrList : TStringList; Str : String; begin // Test 1 : StringListToDelimitedString StrList := TStringList.Create; Str := ''; StrList.Add ( 'Hello1' ); StrList.Add ( 'Hello2' ); StrList.Add ( 'Hello3' ); StrList.Add ( 'Hello4' ); Str := StringListToDelimitedString ( StrList, ';' ); Results.Lines.Add ( Str ); StrList.Free; end; end. Please devise a solution and if possible, some explanation. Alternatives are welcome too.

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• How to trigger the event together on each two deferent class.

  - by XBasic3000

  I have two object class on a single unit, is it posible to trigger the two events? let say the FIRSTCLASS event is fired, The SECONDCLASS also will fired? Assuming...... //{Class 1}------------------------------------------------------------- type TOnEventTrigger = procedure(Sender : Tobject; Value :integer); TMyFirstClass = Class(Tcomponent) private .... public .... OnEventTrigger : TOnEventTrigger read Fevent write Fevent; end; procedure TMyFirstClass.FEvnt(Sender : Tobject; Value :integer); begin // here is normaly triggers the event // if Assigned(OnEventTrigger) then OnEventTrigger(Self,FSomevalue); // POSTMessage(GetForegroundWindow,WM_USER+3,0,0); // this is what i did here to get the result of FSomevalue // but this is not ideal. It work only on focus window. end; //{Class 2}------------------------------------------------------------- type TOnEventTrigger = procedure(Sender : Tobject; Value :integer); TMySecondClass = Class(Tobject) private .... public .... OnEventTrigger : TOnEventTrigger; read Fevent write Fevent; end; procedure TMySecondClass.FEvnt(Sender : Tobject; Value :integer); begin // I wanted here to trigger, whenenver the above is fired // if Assigned(OnEventTrigger) then OnEventTrigger(Self,FSomevalue); end;

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• Transferring Data Directly between 2 Connections in Indy (TIdContext)

  - by killercode

  ive a sever running TIdTCPServer, and Client Using Web Browser (or any other software) to Communicate, i dunno the protocol, but what im trying to do is to Send The Data between the client and another Connection (Both Connected to the same TIdTCPServer) for example the data sent by the first client is transmitted to the second client, and the data sent by the second client is transmitted to the first client, like a proxy (i cant really use a proxy server since its just this one condition) and the TIdTCPServer should still be receiving other clients and processing their data. i stumbled upon the first line of code, since TIdContext.Connection.Socket.ReadLn requires a Delimiter, and the Client's Protocol is unknown to the server. any ideas? thanks.

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• Attributes don't inherit?

  - by Stebi

  I played with attributes and assumed that they are inherited but it doesn't seem so: type [MyAttribute] TClass1 = class end; TClass2 = class(TClass1) end; TClass2 doesn't have the Attribute "MyAttribute" although it inherits from Class1. Is there any possibility to make an attribute inheritable? Or do I have to go up the class hierarchy and search for attributes?

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• Error in my OO Generics design. How do I workaround it?

  - by John

  I get "E2511 Type parameter 'T' must be a class type" on the third class. type TSomeClass=class end; ParentParentClass<T>=class end; ParentClass<T: class> = class(ParentParentClass<T>) end; ChildClass<T: TSomeClass> = class(ParentClass<T>) end; I'm trying to write a lite Generic Array wrapper for any data type(ParentParentClass) ,but because I'm unable to free type idenitifiers( if T is TObject then Tobject(T).Free) , I created the second class, which is useful for class types, so I can free the objects. The third class is where I use my wrapper, but the compiler throws that error. How do I make it compile?

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• How to resolve “Unit JclCompression was compiled with a different version of sevenzip.IOutArchive”?

  - by John

  Hello, There is already a similar question(link).The thing is I don't understand what unit I have to delete. I have installed the latest JCL library and added 'JclCompression' to the uses list in a unit and I get the error: "Unit JclCompression was compiled with a different version of sevenzip.IOutArchive". Please explain to me in a simpler way how to resolve the problem. Thanks in advance!

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• How to test using conditional defines if the application is Firemonkey one?

  - by Gad D Lord

  I use DUnit. It has an VCL GUITestRunner and a console TextTestRunner. In an unit used by both Firemonkey and VCL Forms applications I would like to achieve the following: If Firemonkey app, if target is OS X, and executing on OS X - TextTestRunner If Firemonkey app, if target is 32-bit Windows, executing on Windows - AllocConsole + TextTestRunner If VCL app - GUITestRunner {$IFDEF MACOS} TextTestRunner.RunRegisteredTests; // Case 1 {$ELSE} {$IFDEF MSWINDOWS} AllocConsole; {$ENDIF} {$IFDEF FIREMONKEY_APP} // Case 2 <--------------- HERE TextTestRunner.RunRegisteredTests; {$ELSE} // Case 3 GUITestRunner.RunRegisteredTests; {$IFEND} {$ENDIF} Which is the best way to make Case 2 work?

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• Who's setting TCP window size down to 0, Indy or Windows?

  - by François

  We have an application server which have been observed sending headers with TCP window size 0 at times when the network had congestion (at a client's site). We would like to know if it is Indy or the underlying Windows layer that is responsible for adjusting the TCP window size down from the nominal 64K in adaptation to the available throughput. And we would be able to act upon it becoming 0 (nothing gets send, users wait = no good). So, any info, link, pointer to Indy code are welcome... Disclaimer: I'm not a network specialist. Please keep the answer understandable for the average me ;-) Note: it's Indy9/D2007 on Windows Server 2003 SP2. More gory details: The TCP zero window cases happen on the middle tier talking to the DB server. It happens at the same moments when end users complain of slowdowns in the client application (that's what triggered the network investigation). 2 major Network issues causing bottlenecks have been identified. The TCP zero window happened when there was network congestion, but may or may not be caused by it. We want to know when that happen and have a way to do something (logging at least) in our code. So where to hook (in Indy?) to know when that condition occurs?

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• How can I get an e-mail address out of a string of key=value pairs?

  - by noob

  How can I get some part of string that I need? accountid=xxxxxx type=prem servertime=1256876305 addtime=1185548735 validuntil=1265012019 username=noob directstart=1 protectfiles=0 rsantihack=1 plustrafficmode=1 mirrors= jsconfig=1 [email protected] lots=0 fpoints=6076 ppoints=149 curfiles=38 curspace=3100655714 bodkb=60000000 premkbleft=25000000 ppointrate=116 I want data after email= but up to live.com.?

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