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Kryvich

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Posts posted by Kryvich


  1. To tell the compiler the type of operand, I can advise the following:

    1. Replace array of Integer with TArray<Integer>. (In 10.3 Rio it is the same type.)
    2. Create a helper function:
    function AsArray(const [ref] Arr: TArray<Integer>): TArray<Integer>; inline;
    begin
      Result := Arr;
    end;
    ...
        b := r = AsArray([10]); // It compiles

     


  2. Have you measured how users work with your program? It's possible that an average user use 5-10 reports (tabs) in one session. Then all controls on other tabs just sit in memory, grab GDI resources without need.

     

    It's OK to create the form layouts manually, Delphi has all instruments to make this work easier. But after rising HTML and CSS it has become fashionable to entrust the program with the placement and adjustment of the size of controls on a form. For ex.

     


  3. 2 hours ago, Mike Torrettinni said:

    No... it's actually very simple (looks wise) reporting tool, but organized into 50+ separate tabs (features) on page control(s). So, not cluttered, but all on Main form...

    I presume you didn't put all that controls to the form manually. It's a lot of work. I would use some sort of automation, and create  the appropriate controls on the fly when the tab was selected. Then you'll get 3000/50 = 60 controls at a moment.


  4. 2 hours ago, ConstantGardener said:

    If you have plenty of forms, all created at the begin, your Startup-Time is looooong!

    You're right. A better solution would be to create and initialize a form by request, and then Show(ShowModal)/Close it as needed. The reference to the created form can be saved as a class variable and freed when an application to finish. It makes sense for forms that need to maintain their state. Or for modal dialogs. And you need to ensure that two or more identical forms are not opened at the same time.


  5. 3 hours ago, Mike Torrettinni said:

    I commented out all CreateForm in Project source, except for Main form.

    There is option in the project options (Application | Forms) to select what forms to create when an application starts.


  6. OK I have a workaround for this issue. Try to specify a type of the inline variable.

    procedure TestDictErr_WorkAround;
    var
      Dict: TDictionary<string,TObject>;
    begin
      Dict := TDictionary<string,TObject>.Create;
      for var item: TPair<string,TObject> in Dict do
        Writeln('Key = ', item.Key, ' Name = ', item.Value.ClassName);
    end;

    I cannot guarantee that this code will be correctly compiled. But at least there is no the runtime error anymore.


  7. Another observation. The exception occurs only if the dictionary has the key and/or value of the string type. If I change it to Integer - the exception disappears.

    procedure TestDictErr_IntegerKey_OK;
    var
      Dict: TDictionary<Integer,TObject>;
    begin
      Dict := TDictionary<Integer,TObject>.Create;
      for var item in Dict do
        Writeln('Key = ', item.Key, 'Name = ', item.Value.ClassName);
    end;

    Well, I just found it. For procedure TestDictOK the compiler generates a pair of calls:

    • call @InitializeRecord
    • call @FinalizeRecord

    But for procedure TestDictErr it generates only

    • call @FinalizeRecord

    Program tries to finalize not initialized record and falls.

    P.S. Is there a bug bounty program for Delphi? :) 

    https://quality.embarcadero.com/browse/RSP-23417


  8. Hi, I try to adopt outstanding and free Pas2js transpiler to Delphi language. My main development IDE is Delphi CE Rio, so I decided to try a new Delphi syntax: generic collections and inline variables. And stumbled upon a runtime error. The code (simplified):

    program TestInlineVarForDictionary;
    {$APPTYPE CONSOLE}
    {$R *.res}
    
    uses SysUtils, Generics.Collections;
    
    procedure TestDictErr;
    var
      Dict: TDictionary<string,TObject>;
    begin
      Dict := TDictionary<string,TObject>.Create;
      for var item in Dict do
        Writeln('Key = ', item.Key, 'Name = ', item.Value.ClassName);
    end;
    
    procedure TestDictOK;
    var
      Dict: TDictionary<string,TObject>;
      item: TPair<string,TObject>;
    begin
      Dict := TDictionary<string,TObject>.Create;
      for item in Dict do
        Writeln('Key = ', item.Key, 'Name = ', item.Value.ClassName);
    end;
    
    begin
      try
        //!!TestDictOK;
        TestDictErr;
      except
        on E: Exception do begin
          Writeln(E.ClassName, ': ', E.Message);
          Write('Press Enter to continue...');
          Readln;
        end;
      end;
    end.

    This program causes Exception class $C0000005 with message 'access violation at 0x0040a86e: write of address 0x0040a29e'. Can you confirm it? Is it a bug in the compiler or/and RTL, or am I misusing the new syntax?

    It's interesting: if you uncomment TestDictOK that does enumeration in old-style, the exception will disappear!


  9. @haentschman It's always better to have named constants instead of numbers. Say you want to swap 2nd and 6th bits in some structure's field. Then you need to scan all your program and check all places where these bits are used. But if you used an enumeration from the start, you just swap these bits in the declaration:

    type
      TMyEnum = (mb0, mb5, mb2, mb3, mb4, mb1, mb6, mb7);

    Of course instead of mb0, mb1 etc. should be really meaningful names, without numbers.

    • Haha 1

  10. You can write it as

    If ((b and $01) > 0) or ((b and $08) > 0) or ((b and $80) > 0) then ...

    Or you can create an enumeration and use meaningful names for each bit.

    type
      TMyEnum = (mb0, mb1, mb2, mb3, mb4, mb5, mb6, mb7);
      TMyBits = set of TMyEnum; // = Byte in size
    
    function Test: Byte;
    var
      mbs: TMyBits;
    begin
      mbs := [mb0, mb3, mb7];
      Byte(mbs) := $89; // It's equivalent of mbs := [mb0, mb3, mb7];
      if mbs * [mb0, mb3, mb7] <> [] then // If one of bit is set
        ;//...
      if mbs * [mb0, mb3, mb7] = [mb0, mb3, mb7] then // If all 3 bits are set
        ;//...
      if mbs - [mb0, mb3, mb7] = [] then // If no other bits are set
        ;//...
      Include(mbs, mb1); // Set 2nd bit
      mbs := mbs - [mb3, mb7]; // Unset 4th and 8th bit
      //etc...
      Result := Byte(mbs);
    end;

    It's always better to deal with clearly named typed variables and constants.

    • Like 4

  11. I would write it as 

    localVar := ParameterValue;
    if localVar = None then
      localVar := DefaultValue;

    Presume that ParameterValue is assigned in most cases, then DefaultValue will not be accessed in most cases.

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