Alberto Paganini

Hello, I am thinking of buying a mini PC and installing Delphi CE. I chose the mini PC mainly because of its small footprint. I am not a professional programmer, so I would not use it for 8+ hours every day. What do you recommend in terms of CPU, RAM, SDD size, etc.? Is it a good idea? Many thanks Alberto

Hello again Thanks for this advice, my monitor had 1 VGA and 1 DVI. I took this onboard and connected one PC to one monitor port and the other PC to another. Then purchased a USB hub and plugged the keyboard and the mouse (and I still have two more USB ports available). All I have to do is to switch one USB cable and I can control one of the two PCs Thank you Alberto

But don’t you need any hardware to connect all the hardware? I want to make clear I want to use one computer at the time I don’t want to keep both machines on at the same time. Many thanks Alberto

Hello, I took the advice and compared the performance of the N100 against my desktop CPU single thread. I decided to spend a little more and get something that would perform better. In the end, taking advantage of a deal, I purchased this one: https://www.amazon.co.uk/dp/B0CBJRZ1WY?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 I don't want to get rid of the old desktop and want to switch between desktop and Mini PC easily. I was looking into a KVM switch. No problem with the mouse and keyboard as they both have USB connectors, the only issue is the monitor which has a DVI connector like this one https://www.amazon.co.uk/Benfei-Bidirectional-Female-Adapter-Gold-Plated-DVI-Male-HDMI-2-Pack/dp/B07CXY79KR?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&smid=ABI01N1FCUZG9&th=1 while the Mini PC has HDMI ports. How can I connect the KVM switch to the Mini PC? The idea is to purchase one of these KVM switches https://www.amazon.co.uk/dp/B0D5XSXHCH/?coliid=I1QSRNJHGDRMZN&colid=3JBTT5GDUAMXQ&psc=1&ref_=list_c_wl_gv_ov_lig_pi_dp and connect the old desktop to the switch via DVI cables. To connect the Mini PC to the switch, I have found these cables https://www.amazon.co.uk/dp/B0CDRSP469/?coliid=I2C187CZ18BSFU&colid=3JBTT5GDUAMXQ&ref_=list_c_wl_gv_ov_lig_pi_dp&th=1 Will this work? Do I need anything else? Would you recommend it? Many thanks Alberto

Hello again, I read your previous comments, and I hear you. Honestly, I thought every PC was built in China, or at least all the components were made in China. I am more than willing to look into exceptions if you can point them out. I looked into Beelink forum and it seems TPM is supported by their motherboards but sometimes it's not straightforward to enable. The preinstalled Windows is definitely, a customised version. I chose Amazon because I thought a return would be straightforward in case something goes wrong. Am I wrong ? Why are you avoiding Amazon these days ? If there is a better solution please let me know and I will look into that too. I wish I had the knowledge and confidence to do that, Anders. At the first hurdle, I would not be able to progress. Many thanks for your help Alberto

Hello again, Thank you very much to everybody for your answers. Just to clarify a few points, the budget I have is £ 250 max (EUR 300). In addition to Delphi, I would use it as an everyday PC (web browsing, MS Office). I am not a gamer therefore I don't need much power. I am looking for a new machine because I have an old one with Win 7 32bit. This is still working perfectly but no software has been updated and the performance is not the one that used to be. I will keep this machine though. Back to the original question, this is the hardware I have in mind 16GB RAM 512GM HD OS Windows but I can purchase Win 11 Graphic card being a non gamer I am not too bothered memory slots 2 HDMI+at least 2 fast USB (with USB hubs I can add more) I have already monitor, mouse, keyboard I have found these two mini PC on Amazon https://www.amazon.co.uk/Generation-Processors-Mini-PC-TRIGKEY/dp/B09VB6RK5L/ref=sr_1_19?crid=28IW58GPKU5WV&dib=eyJ2IjoiMSJ9.Osz6FijRchMrjKfN7_mprD5kJMeJeADwENYLX9JPUZJCQuGq0th04V9qLysT9Jc60OxgNyG6GlqXroxmyD8pes3k-DSrFCWMKgtRVGw3YjH5IextFntZvStnGurGD0wQsrU1ntJ-zutshySY9VH9ViU4X1H4lxw2_eVkf5uQxHC7RnFGXc5fX2j6H7_qJuF3h6qikvmW4qjm2o396qjmYq3f555HdRy9jbYVCz-BL2gT5roM_BsidwUKZvuEwkc_JZ5c8CQNN9Ow9LH2l0gWoNY811EqDyMygFKvCJN-x8A.4i5XU5kcvaFNGbFIzji5yeUnhnuLdZ4RLx7JPC2j0kk&dib_tag=se&keywords=mini+pc&nav_sdd=aps&qid=1730325108&refinements=p_36%3A9708205031%2Cp_n_feature_browse-bin%3A21740491031%2Cp_n_feature_twenty-eight_browse-bin%3A49894983031%2Cp_n_feature_eight_browse-bin%3A27344122031&rnid=27344119031&s=computers&sprefix=mini+pc&sr=1-19&ufe=app_do%3Aamzn1.fos.d11e5925-8655-4946-ae2d-1a23abeb136b https://www.amazon.co.uk/Beelink-Lake-N100-Processor-Computer-MINI-S12/dp/B0BZGPTLPG/ref=sr_1_3?crid=28IW58GPKU5WV&dib=eyJ2IjoiMSJ9.oeSF7jwpawC-6vtsOXgkoJbHW7PRaFeeyFzOEbg3j8Kg-lbsPNmhBf9AZjllSzl4U4sWr-rrpo4eYatk3rR-SmcytxKW_H92trvDahZRGZjH8Mkta4mjfhV4-J7ejploO7fY5k8dAZyH71hATzKYnC8p_fCBYyKu4syDdpa1RQahYVivm8WmV_UgQC_JZEwECnNN-NLK55hR-Vy59DkM5Jm7KH6qlSmynPqIRr3vo5TRY5gEE8Bn_T2C1JrHSo2fU5GSlLn99nTCMl--SMC_ryiI1BjffrLKT1qppM1UsxM.hj5DpUFZ-DgbHkEKC1zsD7QwlY2fOMZQLrx3DTZeqRU&dib_tag=se&keywords=mini%2Bpc&nav_sdd=aps&qid=1730325219&refinements=p_36%3A20000-25000%2Cp_n_feature_browse-bin%3A21740491031%2Cp_n_feature_twenty-eight_browse-bin%3A49894983031%2Cp_n_feature_eight_browse-bin%3A27344122031&rnid=9708204031&s=computers&sprefix=mini%2Bpc&sr=1-3&ufe=app_do%3Aamzn1.fos.d11e5925-8655-4946-ae2d-1a23abeb136b&th=1 The reason why I chose Amazon is because if something goes wrong during the warranty period there is no problem in replacing the machine or getting a refund.

Hello, I am trying to update DSharp to the latest release. Before doing that I updated Spring4D successfully. When I tried to update DSharp and build DSharp.Core.DelphiXE2.bpl I had the error message "[DCC Error] DSharp.Collections.Iterators.pas(54): E2170 Cannot override a non-virtual method" Here below is the excerpt of the unit with line 54 TCustomIterator<T> = class(TIterator<T>) private fProc: TIteratorProc<T>; public constructor Create(const proc: TIteratorProc<T>); function Clone: TIterator<T>; override; function MoveNext: Boolean; override; // line 54 end; Any idea of what I am missing out on? Many thanks Alberto

Hello, Isn't the download still available ? Is there an alternative link ? Many thanks Alberto

Hello, Isn't there a 32 bit version of the software ?

Hello, I have a problem with a Win32 application using Indy. All of a sudden it throws me the following error message: "Error connecting with SSL. error 1409442E:SSL routine:ssl3_read_bytes:tlsv1 alert protocol version" In the beginning, I supposed it had something to do with an obsolete version I manage in my source. The following is the only place in my source where I set the SSL version and it supports the version 1.2 function TConnectionClass.GetToken: Boolean; var LJSONObject: TJSONObject; LJSONValue: TJSONValue; {$IFDEF VER230} LJSONPair: TJSONPair; {$ENDIF} LJSONToken: TJSONValue; IdHTTP: TIdHTTP; IdSSL: TIdSSLIOHandlerSocketOpenSSL; IdLogFile: TIdLogFile; sList: TStringList; begin Result := False; FToken := ''; IdHTTP := TIdHTTP.Create(nil); try IdHTTP.HTTPOptions := IdHTTP.HTTPOptions + [hoForceEncodeParams]; IdHTTP.HandleRedirects := True; IdSSL := TIdSSLIOHandlerSocketOpenSSL.Create(IdHTTP); IdSSL.SSLOptions.SSLVersions := [sslvTLSv1, sslvTLSv1_1, sslvTLSv1_2]; IdHTTP.IOHandler := IdSSL; IdLogFile := TIdLogFile.Create(IdHTTP); IdLogFile.Filename := 'c:\' + ChangeFileExt(ExtractFileName(ParamStr(0)), '.log'); IdLogFile.Active := True; IdHTTP.Intercept := IdLogFile; IdHTTP.Request.Accept := 'application/json'; IdHTTP.Request.CustomHeaders.Values['X-Application'] := cBetfair_AppKey; IdHTTP.Request.ContentType := 'application/x-www-form-urlencoded'; sList := TStringList.Create; try sList.Add('username=' + FUserID); sList.Add('password=' + FPassword); LJSONValue := TJSONObject.ParseJSONValue(IdHTTP.Post(URL_LOGIN, sList)); try if LJSONValue is TJSONObject then begin LJSONObject := TJSONObject(LJSONValue); {$IFDEF VER230} LJSONPair := LJSONObject.Get('token'); if LJSONPair <> nil then LJSONToken := LJSONPair.JsonValue else LJSONToken := nil; {$ELSE} LJSONToken := LJSONObject.Values['token']; {$ENDIF} if LJSONToken <> nil then FToken := LJSONToken.Value; end; finally LJSONValue.Free; end; finally sList.Free; end; finally IdHTTP.Free; end; Result := (FToken <> ''); end; I also tried to amend the options into IdSSL.SSLOptions.SSLVersions := [sslvTLSv1_2]; but the error is still the same Then I updated the SSL .dll files in my system32 folder by downloading the latest version of libeay32.dll and ssleay32.dll from here https://indy.fulgan.com/SSL/ and replace the old files with the new ones. I have double-checked and now the .dll have Version file 1.0.2.21 and Version 1.0.2u Despite these attempts, the application still throws me the same exception. Is there anything else I should change? Many thanks Alberto

I would like to replace JsonStringToDateTime with JsonStringToDateTime2 in my code because it is significantly faster. Here below a small example program MyTest; {$APPTYPE CONSOLE} {$R *.res} uses madExcept, madLinkDisAsm, madListHardware, madListProcesses, madListModules, System.SysUtils, Soap.XSBuiltIns; const gNullDate: TDateTime = 2 + 365; {*****************************************************************************************} function JsonStringToDateTime(S: widestring): TDateTime; {*****************************************************************************************} begin result := gNullDate; with TXSDateTime.Create() do begin try XSToNative(S); result := AsDateTime; finally Free; end; end; end; {*****************************************************************************************} function JsonStringToDateTime2(S: widestring): TDateTime; {*****************************************************************************************} var Dummy: string; begin try Result := EncodeDate(StrToInt(Copy(S, 1, 4)), StrToInt(Copy(S, 6, 2)), StrToInt(Copy(S, 9, 2))); Result := EncodeTime(StrToInt(Copy(S, 12, 2)), StrToInt(Copy(S, 15, 2)), StrToInt(Copy(S, 18, 2)), 0); except result := gNullDate; end; end; var TimeResult: TDateTime; a: TDateTime; b: TDateTime; I: Integer; hh, mm, ss, ms: Word; begin a := Now; for i := 0 to 5000 do begin TimeResult := JsonStringToDateTime('2021-02-11T02:25:00.000Z'); end; b := Now - a; DecodeTime(b, Hh, mm, ss, ms); Writeln('JsonStringToDateTime sec:' + IntToStr(ss) + ' msec:+' + IntToStr(ms)); a := Now; for i := 0 to 5000 do begin TimeResult := JsonStringToDateTime2('2021-02-11T02:25:00.000Z'); end; b := Now - a; DecodeTime(b, Hh, mm, ss, ms); Writeln('JsonStringToDateTime2 sec:' + IntToStr(ss) + ' msec:+' + IntToStr(ms)); Readln; end. Can you see any drawbacks in JsonStringToDateTime2 ? Many thanks Alberto

One important part of the application I am working on is to retrieve data from a service provider as often as possible. The function JsonStringToDateTime is called tens of thousands of times from several processes in a few minutes in order to parse the data provided therefore, the faster the function the more times the application can retrieve data. This is one of the most "popular" functions but there are others similar and called as much as this one and I will look into these too. I understand this is just a quick fix, the next step would be to refactor the logic of the application in order to retrieve data and parse it in a better way (maybe parse only the necessary data) but that would require more time and I would like to see some results in the short run. However, for the records here the three versions with the usual quick test. program SoapTest; {$APPTYPE CONSOLE} {$R *.res} uses madExcept, madLinkDisAsm, madListHardware, madListProcesses, madListModules, System.SysUtils, Soap.XSBuiltIns; const gOutOfScopelDate: TDateTime = 2 + 365; {*****************************************************************************************} function JsonStringToDateTime(S: widestring): TDateTime; {*****************************************************************************************} begin result := gOutOfScopelDate; with TXSDateTime.Create() do begin try XSToNative(S); result := AsDateTime; finally Free; end; end; end; {*****************************************************************************************} function JsonStringToDateTime2(S: widestring): TDateTime; {*****************************************************************************************} begin try Result := EncodeDate(StrToInt(Copy(S, 1, 4)), StrToInt(Copy(S, 6, 2)), StrToInt(Copy(S, 9, 2))); Result := Result + EncodeTime(StrToInt(Copy(S, 12, 2)), StrToInt(Copy(S, 15, 2)), StrToInt(Copy(S, 18, 2)), 0); except result := gOutOfScopelDate; end; end; {*****************************************************************************************} function JsonStringToDateTime3(Src: widestring): TDateTime; {*****************************************************************************************} function CharToDigit(aChar: Char): Integer; inline; begin Result := Ord(aChar) - Ord('0'); end; var S: string; pSrc, pDest: PChar; begin SetLength(S, 8); pSrc := Pointer(Src); pDest := Pointer(S); try //date pDest^ := pSrc^; (pDest + 1)^ := (pSrc + 1)^; (pDest + 2)^ := (pSrc + 2)^; (pDest + 3)^ := (pSrc + 3)^; (pDest + 4)^ := (pSrc + 5)^; (pDest + 5)^ := (pSrc + 6)^; (pDest + 6)^ := (pSrc + 8)^; (pDest + 7)^ := (pSrc + 9)^; {(*} Result := EncodeDate( // year CharToDigit(S[1]) * 1000 + CharToDigit(S[2]) * 100 + CharToDigit(S[3]) * 10 +CharToDigit(S[4]), CharToDigit(S[5]) * 10 +CharToDigit(S[6]), //month CharToDigit(S[7]) * 10 +CharToDigit(S[8])); //date {*)} //time pDest^ := (pSrc + 11)^; (pDest + 1)^ := (pSrc + 12)^; (pDest + 2)^ := (pSrc + 14)^; (pDest + 3)^ := (pSrc + 15)^; (pDest + 4)^ := (pSrc + 17)^; (pDest + 5)^ := (pSrc + 18)^; {(*} Result:=Result+EncodeTime( CharToDigit(S[1]) * 10 +CharToDigit(S[2]), //hh CharToDigit(S[3]) * 10 +CharToDigit(S[4]), //mm CharToDigit(S[5]) * 10 +CharToDigit(S[6]), //ss 0//ms ); {*)} except result := gOutOfScopelDate; end; end; const aTimes = 5000; var TimeResult: TDateTime; a: TDateTime; b: TDateTime; I: Integer; hh, mm, ss, ms: Word; begin a := Now; for i := 0 to aTimes do begin TimeResult := JsonStringToDateTime('2021-02-11T02:25:00.000Z'); end; b := Now - a; DecodeTime(b, Hh, mm, ss, ms); Writeln('JsonStringToDateTime sec:' + IntToStr(ss) + ' msec:' + IntToStr(ms)); a := Now; for i := 0 to aTimes do begin TimeResult := JsonStringToDateTime2('2023-03-13T02:25:00.000Z'); end; b := Now - a; DecodeTime(b, Hh, mm, ss, ms); Writeln('JsonStringToDateTime2 sec:' + IntToStr(ss) + ' msec:' + IntToStr(ms)); a := Now; for i := 0 to aTimes do begin TimeResult := JsonStringToDateTime3('2023-03-13T02:25:00.000Z'); end; b := Now - a; DecodeTime(b, Hh, mm, ss, ms); Writeln('JsonStringToDateTime3 sec:' + IntToStr(ss) + ' msec:' + IntToStr(ms)); Readln; end. In all honesty, I didn't think that replacing Copy would make a big difference, obviously, I was wrong. I was under the impression that StrToInt could be replaced but I didn't know how to do. The improvement that the changes suggested by @Fr0sT.Brutal make is very big! Thank you. I hope I have understood all the suggestions. Many thanks Alberto

I was not able to think of anything better in order to transform parts of a string into numbers and then put everything into a TDateTime. Is there an alternative to that, considering that performance is important here?

@emailx45 That is technically correct, there is no "null date" in Delphi. The software I am working on should receive dates >01/01/1901 only. If something goes wrong the procedure assigns 01/01/1901 to Result. Somewhere else the application checks Result and if it is is 01/01/1901 treats this accordingly. I should have renamed it something like gOutOfScopeDate

Yes, sorry I forgot to remove it. Any particular reason for that? I am not trying to be funny here. I just want to understand why this is better. Yes, not a problem in my case.

Ok, I have found out the final issues. It turned out that Windows 7 does not enable TLS 1.2 by default. You have to do it manually by following this process https://support.site24x7.com/portal/en/kb/articles/how-to-check-if-tls-1-2-is-enabled At this stage, the function above started working. Next, I had to add one extra line in a third party code every time TIdSSLIOHandlerSocketOpenSSL is created. The extra line is sslIOHandler.SSLOptions.SSLVersions := [sslvTLSv1_2]; After that, the application started working as before. @Remy LebeauThank you for your help Alberto

It seems I am making progress with this. I have amended the class in a way the application loads the .DLLs residing in the application folder. This is achieved with IdSSLOpenSSLHeaders.IdOpenSSLSetLibPath(). (Thanks to Remi for this post https://stackoverflow.com/questions/13269169/how-to-use-a-dll-outside-of-the-system-path) IdSSLOpenSSL.OpenSSLVersion; confirms now "OpenSSL 1.0.2q 20 Nov 2018" is loaded and this collides with the .DLLs version in the application folder. As far as I can see from the https://www.openssl.org/news/openssl-1.0.2-notes.html the OpenSSL 1.0.2 supports TLS 1.2 for a long time (Jan 2015). Despite that my application still throws "tlsv1 alert protocol version" Is there anything else I should be aware of ? The amended source code is here above if anybody may be interested. Many thanks Alberto function TConnectionClass.GetToken: Boolean; var LJSONObject: TJSONObject; LJSONValue: TJSONValue; {$IFDEF VER230} LJSONPair: TJSONPair; {$ENDIF} LJSONToken: TJSONValue; IdHTTP: TIdHTTP; IdSSL: TIdSSLIOHandlerSocketOpenSSL; IdLogFile: TIdLogFile; sList: TStringList; Path:string; OpenSSLVersion:string; begin begin Result := False; FToken := ''; Path:=ExtractFilePath(ParamStr(0)); IdSSLOpenSSLHeaders.IdOpenSSLSetLibPath(Path); OpenSSLVersion:= IdSSLOpenSSL.OpenSSLVersion; IdHTTP := TIdHTTP.Create(nil); try IdHTTP.HTTPOptions := IdHTTP.HTTPOptions + [hoForceEncodeParams]; IdHTTP.HandleRedirects := True; IdSSL := TIdSSLIOHandlerSocketOpenSSL.Create(IdHTTP); IdSSL.SSLOptions.SSLVersions := [sslvTLSv1, sslvTLSv1_1, sslvTLSv1_2]; IdHTTP.IOHandler := IdSSL; IdLogFile := TIdLogFile.Create(IdHTTP); IdLogFile.Filename := 'c:\' + ChangeFileExt(ExtractFileName(ParamStr(0)), '.log'); IdLogFile.Active := True; IdHTTP.Intercept := IdLogFile; IdHTTP.Request.Accept := 'application/json'; IdHTTP.Request.CustomHeaders.Values['X-Application'] := cBetfair_AppKey; IdHTTP.Request.ContentType := 'application/x-www-form-urlencoded'; sList := TStringList.Create; try sList.Add('username=' + FUserID); sList.Add('password=' + FPassword); LJSONValue := TJSONObject.ParseJSONValue(IdHTTP.Post(URL_LOGIN, sList)); try if LJSONValue is TJSONObject then begin LJSONObject := TJSONObject(LJSONValue); {$IFDEF VER230} LJSONPair := LJSONObject.Get('token'); if LJSONPair <> nil then LJSONToken := LJSONPair.JsonValue else LJSONToken := nil; {$ELSE} LJSONToken := LJSONObject.Values['token']; {$ENDIF} if LJSONToken <> nil then FToken := LJSONToken.Value; end; finally LJSONValue.Free; end; finally sList.Free; end; finally IdHTTP.Free; end; Result := (FToken <> ''); end;

@Remy Lebeau Yes, this is the issue. I have just found out from the provider that "From 1st December only TLS 1.2 and above will be supported". I renamed libeay32.dll and ssleay32.dll in the system32 folder, downloaded the two .DLLs from Github, placed them in the application folder but the error is still the same. The version I have reported is the one found in the properties of the .DLL files. However, the OpenSSLVersion function reports OpenSSL 1.0.0d 8 Feb 2011, and that explains why the .exe is not working any longer. Does it mean my application uses other SSL .DLLs on my hard disk? (yes, I have a few installed by other third-party software. Each of them resides in the relevant application folder) How can I tell my application that the correct .DLL resides in the same folder of the application itself? I don't want to delete the other .DLLs in order not to stop the other applications to work. Many thanks. Alberto

I use FastMM4 to check memory leaks and I noticed the report file " MyApplicatoin+MemoryManager_EventLog.txt" is not deleted automatically once I have amended the source and I run my application again. This way if there are still memory leaks they are added to the existing report and this confuses me. Is there an option in FastMM4 to achieve that I am not aware of or do I have to rely on DeleteFile(...) when I run the application ? Many thanks Alberto

Thank you David, this did the trick !

I did and created this test: program Project3; {$APPTYPE CONSOLE} {$R *.res} uses FastMM4, system.Classes, System.SysUtils; var t:tstringlist; begin t:=TStringList.Create; end. I ran it a number of times and the new reports are appended to the old ones. Obviously there must be something wrong in my FastMM4 settings. I will look into that.

I am just investigating on how this works. Having the following code: program Project3; {$APPTYPE CONSOLE} {$R *.res} uses FastMM4, system.Classes, System.SysUtils; type MyInterface2 = interface ['{8E7BC71F-55EE-4345-8A5B-42C433BE9EBA}'] procedure print; end; MyInterface1 = interface ['{607A66A6-D68C-4980-9FB1-83B325EE9A91}'] procedure SetInterface2(aInterface: MyInterface2); end; TMyClass1 = class(TInterfacedObject, MyInterface1) private RefToInterFace2: MyInterface2; public procedure SetInterface2(aInterface: MyInterface2); end; TMyClass2 = class(TInterfacedObject, MyInterface2) constructor Create(int: MyInterface1); reintroduce; procedure print; end; { TMyClass1 } procedure TMyClass2.print; begin Writeln('TMyClass2.print'); Sleep(1500); end; { TMyClass2 } procedure TMyClass1.SetInterface2(aInterface: MyInterface2); begin RefToInterFace2 := aInterface; RefToInterFace2.print; end; constructor TMyClass2.Create(int: MyInterface1); begin inherited Create; int.SetInterface2(Self); end; var aMyClass1: MyInterface1; aMyClass2: MyInterface2; begin aMyClass1 := TMyClass1.Create; aMyClass2 := TMyClass2.Create(aMyClass1); end. How does TMyClass1 know there is RefToInterFace2 to be set to nil in order to prevent an AV error? Where is RefToInterFace2:=nil invoked from? I mean, TMyClass1 ancestor does not know about RefToInterFace2 and RefToInterFace2 is not set to nil anywhere in TMyClass1 Many thanks Alberto

@Stefan Glienke I have amended the example according to your advice. program Project3; {$APPTYPE CONSOLE} {$R *.res} uses FastMM4, system.Classes, System.SysUtils, Spring; type MyInterface2 = interface ['{8E7BC71F-55EE-4345-8A5B-42C433BE9EBA}'] procedure print; end; MyInterface1 = interface ['{607A66A6-D68C-4980-9FB1-83B325EE9A91}'] procedure SetInterface2(const aInterface: MyInterface2); procedure DoSomethingWithInterface2; end; TMyClass1 = class(TInterfacedObject, MyInterface1) private //RefToInterFace2: Pointer{MyInterface2}; RefToInterFace2: Weak<MyInterface2>; public procedure SetInterface2(const aInterface: MyInterface2); procedure DoSomethingWithInterface2; end; TMyClass2 = class(TInterfacedObject, MyInterface2) private // Ref: MyInterface1; ref: Weak<MyInterface1>; public constructor Create(int: MyInterface1); reintroduce; destructor Destroy; override; // this can be deleted procedure print; end; { TMyClass1 } procedure TMyClass2.print; begin Writeln('TMyClass2.print'); Sleep(1500); end; { TMyClass2 } procedure TMyClass1.DoSomethingWithInterface2; begin if RefToInterFace2 <> nil then begin // MyInterface2(RefToInterFace2).print; RefToInterFace2.Target.print; end; end; procedure TMyClass1.SetInterface2(const aInterface: MyInterface2); begin // RefToInterFace2 := Pointer(aInterface); RefToInterFace2.Target := aInterface; end; constructor TMyClass2.Create(int: MyInterface1); begin inherited Create; if int <> nil then begin Ref.Create(int); Ref.Target.SetInterface2(Self); end; end; destructor TMyClass2.Destroy; begin // if Ref <> nil then // MyInterface1(Ref).SetInterface2(nil); inherited Destroy; end; var aMyClass1: MyInterface1; aMyClass2: MyInterface2; begin aMyClass1 := TMyClass1.Create; aMyClass2 := TMyClass2.Create(aMyClass1); aMyClass1.DoSomethingWithInterface2; end. Is that acceptable? In which case the pointer approach proposed by Remi may cause AV errors? Many thanks Alberto

Hi Remi, I had to amend your code with the following one in order to make the example compile by DX2 procedure TMyClass1.SetInterface2(const aInterface: MyInterface2); begin RefToInterFace2 := Pointer(aInterface); end; The rest is all spot on! I suppose that the advantage to use the second solution is you can call any method of MyInterface1 throughout TMyClass2 by using Ref while in the first one you can do it only in TMyClass2.Create as MyInterface1 is not stored in a variable. Thank you very much for taking the time. Alberto

But If I store the interface in a local variable in TMyClass2, Ref in my example, I have a leak instead. It seems the RTL cannot have access to it. The only way to release the variable is to use a method and call this method from the main begin..end. Here below the minimum example. program Project3; {$APPTYPE CONSOLE} {$R *.res} uses FastMM4, system.Classes, System.SysUtils; type MyInterface2 = interface ['{8E7BC71F-55EE-4345-8A5B-42C433BE9EBA}'] procedure print; end; MyInterface1 = interface ['{607A66A6-D68C-4980-9FB1-83B325EE9A91}'] procedure SetInterface2(aInterface: MyInterface2); procedure DoSomethingWithInterface2; end; TMyClass1 = class(TInterfacedObject, MyInterface1) private RefToInterFace2: MyInterface2; public procedure SetInterface2(aInterface: MyInterface2); procedure DoSomethingWithInterface2; destructor Destroy;override; end; TMyClass2 = class(TInterfacedObject, MyInterface2) private Ref: MyInterface1; public constructor Create(int: MyInterface1); reintroduce; procedure print; end; { TMyClass1 } procedure TMyClass2.print; begin Writeln('TMyClass2.print'); Sleep(1500); end; { TMyClass2 } destructor TMyClass1.Destroy; begin SetInterface2(nil);// this isn not executed inherited; end; procedure TMyClass1.DoSomethingWithInterface2; begin RefToInterFace2.print; end; procedure TMyClass1.SetInterface2(aInterface: MyInterface2); begin RefToInterFace2 := aInterface; end; constructor TMyClass2.Create(int: MyInterface1); begin inherited Create; Ref := int; Ref.SetInterface2(Self); end; var aMyClass1: MyInterface1; aMyClass2: MyInterface2; begin aMyClass1 := TMyClass1.Create; aMyClass2 := TMyClass2.Create(aMyClass1); aMyClass1.DoSomethingWithInterface2; aMyClass1.SetInterface2(nil);// this releases the variable end. Is this the only way to release the pointer in the variable or is there a better way? If I add a destructor that is not executed. Many thanks Alberto