Migrace na objektový model. Použití třídy uvnitř TForm

 

Program ve FreePascalu - IDE Lazarus. Zde je jsou první dva soubory: projekt a soubor s objektem. program project1; {$mode objfpc}{$H+} uses {$IFDEF UNIX} cthreads, {$ENDIF} {$IFDEF HASAMIGA} athreads, {$ENDIF} Interfaces, // this includes the LCL widgetset Forms, uMain, uSettings { you can add units after this }; {$R *.res} begin RequireDerivedFormResource := True; Application.Scaled := True; Application.Initialize; Application.CreateForm(TForm1, Form1); Application.Run; end. umain.lfm: object Form1: TForm1 Left = 352 Height = 240 Top = 250 Width = 320 Caption = 'Form1' ClientHeight = 240 ClientWidth = 320 OnClose = FormClose object Memo1: TMemo Left = 8 Height = 184 Top = 8 Width = 296 Lines.Strings = ( 'Memo1' ) TabOrder = 0 end object Button1: TButton Left = 16 Height = 25 Top = 200 Width = 75 Caption = 'Save' TabOrder = 1 OnClick = Button1Click end object Button2: TButton Left = 192 Height = 25 Top = 200 Width = 75 Caption = 'Load' TabOrder = 2 OnClick = Button2Click end end

Looks like you've provided code snippets for a Lazarus project written in Free Pascal. The code defines a simple GUI application with a form that includes a memo (text area) and two buttons: "Save" and "Load." The form layout is described in the umain.lfm file using Lazarus' form designer.

The code indicates that the main form's unit is uMain and the form class is TForm1. This class likely contains event handlers for the button clicks and form close events.

Here's a breakdown of the code:

1. The main program (project1):

   • The program uses the {$mode objfpc}{$H+} directive to enable object-oriented programming mode and use modern object features.
   • It includes various units, such as Interfaces, Forms, uMain, and uSettings.
   • {$R *.res} specifies that resources (like icons) are linked into the executable.
   • The program's entry point initializes the application, creates an instance of TForm1 (defined in uMain), and starts the application's event loop.

2. The form definition (umain.lfm):

   • The form TForm1 has a defined layout with properties like Left, Height, Top, Width, and Caption.
   • It includes a TMemo component for text input and display.
   • Two TButton components are present: "Save" and "Load."
   • Event handlers are assigned using the OnClick property for the buttons and the OnClose property for the form.

It appears that the functionality for saving and loading data from the memo is implemented in the event handlers. The Button1Click and Button2Click procedures in the uMain unit are likely where you would implement the logic for saving and loading data to/from the TMemo component.

If you need specific help with implementing functionalities or understanding specific parts of the code, feel free to ask!

Q:

Dále posílám soubor s modulem uSettings. Ohledně tohoto modulu mě bude zajímat, zda by bylo možné ho převést na třídu a následně aby hlavní formulář zdědil vlastnosti a metody od uSettings. Tzn. můj dotaz bude směřovat k tomu, zda je možné se vyhnout použití globální proměnné. Abyste porozuměl celému programu, předám vám ještě modul unit uMain ... unit uSettings; {$mode ObjFPC}{$H+} interface uses Classes, SysUtils, IniFiles; type TSetting = record Name: string; FileName: string; Path: string; Files: TStringList; FilesCount: Integer; end; TSettings = array of TSetting; function FreeSettings(var ASettings: TSettings): Boolean; function SaveSettings(const AFilename: string; const ASettings: TSettings): Boolean; function LoadSettings(const AFilename: string; var ASettings: TSettings): Boolean; var // your shared global object to play with GSettings: TSettings; implementation function FreeSettings(var ASettings: TSettings): Boolean; var i: Integer; begin Result := False; for i := High(ASettings) downto Low(ASettings) do begin ASettings[i].Files.Free; ASettings[i].FilesCount := 0; ASettings[i].FileName := ''; ASettings[i].Name := ''; ASettings[i].Path := ''; end; SetLength(ASettings, 0); Result := Length(ASettings) = 0; end; function SaveSettings(const AFilename: string; const ASettings: TSettings): Boolean; var I, J: Integer; Ini: TIniFile; begin Result := False; if Length(ASettings) = 0 then Exit; if ForceDirectories(ExtractFilePath(AFilename)) then begin if FileExists(AFilename) then if (not DeleteFile(AFilename)) then Exit; Ini := TIniFile.Create(AFilename); try Ini.WriteInteger('Groups', 'Count', Length(ASettings)); for i := Low(ASettings) to High(ASettings) do begin Ini.WriteString('Groups', 'Name' + IntToStr(I), ASettings[I].Name); Ini.WriteString('Groups', 'FileName' + IntToStr(I), ASettings[I].FileName); Ini.WriteString('Groups', 'Path' + IntToStr(I), ASettings[I].Path); for j := 0 to Pred(ASettings[i].Files.Count) do Ini.WriteString('Files', 'Group_' + IntToStr(I) + '_File' + IntToStr(J), ASettings[I].Files[J]); Ini.WriteInteger('Groups', 'FilesCount' + IntToStr(I), ASettings[I].FilesCount); end; Result := True; finally ini.Free; end; end; end; function LoadSettings(const AFilename: string; var ASettings: TSettings): Boolean; var i, j, cnt: Integer; ini: TIniFile; begin Result := False; if Length(ASettings) > 0 then FreeSettings(ASettings); if (not FileExists(AFilename)) then Exit; ini := TIniFile.Create(AFilename); try cnt := ini.ReadInteger('Groups', 'Count', 0); SetLength(ASettings, cnt); for i := 0 to Pred(cnt) do begin ASettings[i].Name := ini.ReadString('Groups', 'Name' + IntToStr(i), ''); ASettings[i].FileName := ini.ReadString('Groups', 'FileName' + IntToStr(i), ''); ASettings[i].Path := ini.ReadString('Groups', 'Path' + IntToStr(i), ''); ASettings[i].FilesCount := ini.ReadInteger('Groups', 'FilesCount' + IntToStr(I), 0); ASettings[i].Files := TStringList.Create; try for j := 0 to Pred(ASettings[i].FilesCount) do ASettings[i].Files.Add(ini.ReadString('Files', 'Group_' + IntToStr(I) + '_File' + IntToStr(J), '')); finally Result := (Length(ASettings) > 0); end; end; finally ini.Free; end; end; end.

Sure, it looks like you have provided the uSettings unit which handles saving and loading settings using an INI file. To achieve your goal of converting this module into a class and inheriting its properties and methods in the main form, you can follow these steps:

1. Create a Class for Settings: Transform the TSetting record and the functions in the uSettings unit into a class. You can name this class, for example, TSettingsManager. Move all the code inside the class declaration and change the global variables like GSettings into instance variables.

type
  TSettingsManager = class
  private
    FSettings: TSettings; // Instance variable to store settings

  public
    constructor Create;
    destructor Destroy; override;

    function FreeSettings: Boolean;
    function SaveSettings(const AFilename: string): Boolean;
    function LoadSettings(const AFilename: string): Boolean;
  end;

Move the function implementations to the corresponding methods inside the class.

Inheritance and Usage: Inherit this TSettingsManager class in your main form's class, TForm1. This way, the main form will have access to all the methods and properties of the settings manager.

2. TForm1 = class(TForm)
     // ... existing components ...
   
   private
     FSettingsManager: TSettingsManager; // Instance of the settings manager
   
   public
     constructor Create(AOwner: TComponent); override;
     destructor Destroy; override;
   
     // ... existing event handlers ...
   
   end;
   

   In your TForm1 constructor, create an instance of TSettingsManager and assign it to the FSettingsManager variable. Similarly, in the destructor, free the FSettingsManager instance.

3. Code Migration: Now you need to adjust the code in your TForm1 methods that were using the global GSettings variable to use the instance of TSettingsManager instead. Update references to GSettings to FSettingsManager.

This refactoring will encapsulate the settings functionality within the TSettingsManager class, allowing you to inherit its properties and methods into the main form without using global variables. This approach promotes better encapsulation, separation of concerns, and code organization.

Keep in mind that while the general steps for converting this into a class are outlined here, the actual implementation details might require adjustments based on how your application is structured and how the TSettings structure is used within other parts of your code.

Q:

Poslední soubor je program samotný: unit uMain; {$mode objfpc}{$H+} interface uses Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, uSettings; type { TForm1 } TForm1 = class(TForm) Button1: TButton; Button2: TButton; Memo1: TMemo; procedure Button1Click(Sender: TObject); procedure Button2Click(Sender: TObject); procedure FormClose(Sender: TObject; var CloseAction: TCloseAction); private public end; var Form1: TForm1; implementation {$R *.lfm} { TForm1 } procedure TForm1.Button1Click(Sender: TObject); var Filename: string; begin FreeSettings(GSettings); SetLength(GSettings, 2); GSettings[0].Name := 'Group1'; GSettings[0].FileName := 'myimage1.jpg'; GSettings[0].Path := '/path/to/group_of_images_1'; GSettings[0].Files := TStringList.Create; GSettings[0].Files.Add('myimage1.txt'); GSettings[0].Files.Add('myimage2.txt'); GSettings[0].FilesCount := GSettings[0].Files.Count; GSettings[1].Name := 'Group2'; GSettings[1].FileName := 'myimage.jpg'; GSettings[1].Path := '/path/to/group_of_images_2'; GSettings[1].Files := TStringList.Create; GSettings[1].Files.Add('myimage3.txt'); GSettings[1].Files.Add('myimage4.txt'); GSettings[1].FilesCount := GSettings[1].Files.Count; Filename := IncludeTrailingBackslash(GetEnvironmentVariable('APPDATA')) + 'ishta\settings.ini'; SaveSettings(Filename, GSettings); FreeSettings(GSettings); end; procedure TForm1.Button2Click(Sender: TObject); var Filename: string; i, j: Integer; begin FreeSettings(GSettings); Filename := IncludeTrailingBackslash(GetEnvironmentVariable('APPDATA')) + 'ishta\settings.ini'; if LoadSettings(Filename, GSettings) then begin Memo1.Lines.BeginUpdate; Memo1.Clear; Memo1.Lines.Add(Format('Found %d groups', [Length(GSettings)])); for i := Low(GSettings) to High(GSettings) do begin Memo1.Lines.Add(Format('Group: %s', [GSettings[i].Name])); Memo1.Lines.Add(Format('Group: %s - Filename: %s', [GSettings[i].Name, GSettings[i].FileName])); Memo1.Lines.Add(Format('Group: %s - Path: %s', [GSettings[i].Name, GSettings[i].Path])); for j := 0 to Pred(GSettings[i].Files.Count) do Memo1.Lines.Add(Format('Group: %s - File: %s: ', [GSettings[i].Name, GSettings[i].Files.Strings[j]])); end; Memo1.Lines.EndUpdate; end; end; procedure TForm1.FormClose(Sender: TObject; var CloseAction: TCloseAction); begin FreeSettings(GSettings); end; end.

Thank you for providing the uMain unit. Here, you have the implementation of the main form where you use the settings from the uSettings module. To migrate the settings handling to the TSettingsManager class, you'll need to make the following changes:

1. Create an instance of TSettingsManager: In your TForm1 class, create an instance of TSettingsManager in the constructor and free it in the destructor.

constructor TForm1.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FSettingsManager := TSettingsManager.Create;
end;

destructor TForm1.Destroy;
begin
  FSettingsManager.Free;
  inherited Destroy;
end;

Update Button1Click: In your Button1Click method, replace the usage of GSettings with the instance of TSettingsManager.

procedure TForm1.Button1Click(Sender: TObject);
var
  Filename: string;
begin
  FSettingsManager.FreeSettings;
  FSettingsManager.Settings := ...; // Initialize your settings here
  Filename := IncludeTrailingBackslash(GetEnvironmentVariable('APPDATA')) + 'ishta\settings.ini';
  FSettingsManager.SaveSettings(Filename);
  FSettingsManager.FreeSettings;
end;

Update Button2Click: Similarly, update the Button2Click method.

procedure TForm1.Button2Click(Sender: TObject);
var
  Filename: string;
begin
  FSettingsManager.FreeSettings;
  Filename := IncludeTrailingBackslash(GetEnvironmentVariable('APPDATA')) + 'ishta\settings.ini';
  if FSettingsManager.LoadSettings(Filename) then
  begin
    Memo1.Lines.BeginUpdate;
    Memo1.Clear;
    Memo1.Lines.Add(Format('Found %d groups', [FSettingsManager.SettingsCount]));
    for i := 0 to FSettingsManager.SettingsCount - 1 do
    begin
      Memo1.Lines.Add(Format('Group: %s', [FSettingsManager.Settings[i].Name]));
      Memo1.Lines.Add(Format('Group: %s - Filename: %s', [FSettingsManager.Settings[i].Name, FSettingsManager.Settings[i].FileName]));
      Memo1.Lines.Add(Format('Group: %s - Path: %s', [FSettingsManager.Settings[i].Name, FSettingsManager.Settings[i].Path]));
      for j := 0 to FSettingsManager.Settings[i].FilesCount - 1 do
        Memo1.Lines.Add(Format('Group: %s - File: %s: ', [FSettingsManager.Settings[i].Name, FSettingsManager.Settings[i].Files[j]]));
    end;
    Memo1.Lines.EndUpdate;
  end;
end;

Update FormClose: Finally, update the FormClose method to use the FSettingsManager.

4. procedure TForm1.FormClose(Sender: TObject; var CloseAction: TCloseAction);
   begin
     FSettingsManager.FreeSettings;
   end;
   

Remember that while I've provided you with the overall steps and structure, you might need to make some adjustments based on the details of your application and how the settings are used. This approach should help you encapsulate the settings management within the TSettingsManager class without relying on global variables.

Q:

Je to vše co jako začátečník potřebuju znát, nebo potřebuju ještě znát nějaké další detaily pro migraci?

Pro migraci existujícího kódu na konkrétní architekturu tříd a objektů jste obdržel základní návod. Nicméně ještě existuje několik oblastí, na které byste se mohl zaměřit, zejména pokud jste začátečník:

1. Pochopení Tříd a Objektů: Dobré porozumění konceptů tříd, objektů, dědičnosti, konstruktorů a destruktorů je klíčové pro efektivní migraci na objektový model. Mohli byste si přečíst více o těchto základních principech objektově orientovaného programování.

2. Testování: Po provedení migrace je důležité provést důkladné testování vaší aplikace, aby se zajistilo, že všechny funkce stále pracují, jak mají. Otestujte různé scénáře a situace, abyste zjistili, zda všechny změny probíhají hladce.

3. Ověření Výkonnosti: Velké změny v kódu mohou ovlivnit výkonnost aplikace. Mějte na paměti, že pokud vytváříte nebo ukládáte velké množství dat, může to ovlivnit rychlost vaší aplikace. Prověřte, jestli výkon splňuje vaše očekávání.

4. Správa Chyb: Migrace může přinést chyby nebo neočekávané chování. Berte si čas na testování a zabezpečte, abyste měli postup, jak zjistit a opravit problémy, které by se mohly objevit.

5. Dokumentace: Při migraci je důležité udržet si aktualizovanou dokumentaci kódu. Zaznamenejte provedené změny, vysvětlete důvody a základní funkce nového objektového návrhu.

6. Konzistence Stylu: Sledujte konzistenci stylu kódu. Pokud pracujete v týmu nebo na větším projektu, je důležité dodržovat sjednocený styl zápisu kódu, abyste usnadnili spolupráci a udržování kódu.

7. Další Funkcionalita: Při tvorbě objektového modelu můžete zvážit, zda by jiné části aplikace také mohly být refaktorovány do tříd a objektů. To může zlepšit modularitu a zpřehlednit kód.

8. Naučení se Zdrojům: Pokud se chcete dozvědět více o objektově orientovaném programování a Free Pascal/Lazarus, existuje mnoho online zdrojů, tutoriálů a kurzů, které vám mohou pomoci rozvíjet vaše znalosti.

Pamatujte si, že proces migrace může být postupný a učící se zkušeností. Důležité je mít trpělivost a postupovat krok za krokem. Pokud se objeví problémy, nebojte se hledat rady a řešení.