Class in Class/Osztály az osztályban (Multilang)

[TheProgrammer]

How can i create Class in class?
Hogyan csinálhatok osztályt az osztályban?

Example/Példa:

Code: [Select]

type
  TClassInClass = class
    var1, var2, var3 : String;
  end;

  TMyClass = class
    ClassInClass  : TClassInClass;
    function classfunction : Boolean;
    procedure classprocedure(const const1, const2, const3 : WideString);
  end; 

or/vagy

Code: [Select]

type
  TCecordInClass = record
    var1, var2, var3 : String;
  end;

  TMyClass = class
    CecordInClass : TCecordInClass;
    function classfunction : Boolean;
    procedure classprocedure(const const1, const2, const3 : WideString);
  end;
These codes don't work...
Ez a kód nem működik...

Error: Project xy raised exception class 'External:SIGSEGV'.

My System setting: Windows 7 32bit / Lazarus 0.9.30 and FPC 2.4.2

This is Unit file, not program...
Ez itt modul, nem program kód...

Mode: {$mode objfpc}{$H+}
My Uses list:
Ezeket a forrásokat használom:
Classes, SysUtils, Math, ActiveX, ComObj, Variants;

(I use Ole WMI function...)
(WMI Ole funkciót használok...)

Code: [Select]


procedure TMyClass.classprocedure(const const1, const2, const3 : WideString);
begin
ClassInClass.Var := FWbemObject.Properties_.Item('L2CacheSize').Value;
end;

All Code run in TThread class in Program...
AZ összes kód egy Programszál osztályban fut...

[Leledumbo]

The problem is not class in class (because it passes compiling step and generates executable), but how you use it.

ClassInClass.Var := FWbemObject.Properties_.Item('L2CacheSize').Value;

Have you initialized ClassInClass?

[TheProgrammer]

I defined "ClassInClass" in type and I'd like to add value in "MyClass" procedure...
Definiáltam a típusoknál a "ClassInClass"-t és szeretnék adni neki egy értéket a "MyClass" procedurájában...

Defined: see examples...
Definíció: lásd példa....

[TheProgrammer]

ClassInClass.Var := FWbemObject.Properties_.Item('L2CacheSize').Value;

Correction:
Javítás:
ClassInClass.Var1 := FWbemObject.Properties_.Item('L2CacheSize').Value;

I would like to do this in program:
Ezt szeretném elérni a programban:

MyClass.classprocedure('xy', 'xy', 'xy');

Label.Caption := MyClass.ClassInClass.Var1

[Arbee]

What Leledumbo refers to is whether you have created an instance of ClassInClass, which would normally be done in the constructor of TMyClass.  Without it you will definitely get a SIGSEGV.

If you also get the SIGSEGV when using a Record, then it suggests the real issue is with the FWemObject.  Is that properly instantiated?

[JD]

I assume that you are familiar with associative classes & composite classes. If not read this
http://delphi.about.com/od/course/a/delphi_oop19.htm

[TheProgrammer]

Is that properly instantiated?

Have you initialized ClassInClass?

How can i initalised the ClassInClass? This part I do not know...
Hogyan tudok inicializálni? Ezt a részét nem ismerem...

[TheProgrammer]

I have to do "ClassInClass" variables in "Implementation" section? <-This by Google Translation
Kell csinálnom "ClassInClass" változókat az "Implementation" részhez?

Sorry, My English translation is not perfect...

[JD]

You can initialize TClassInClass in 2 places

a) inside the constructor of TMyClass. TMyClass will then be a composite class. TMyClass will then own TClassInClass.

b) elsewhere in the program. TMyClass will then be associated with TClassInClass & the two can have independent lifespans.

[Carver413]

When you declare a class in a class you end up with a nil pointer that represents where the class should go. only after you assign it

Code: [Select]

  CecordInClass:= TCecordInClass.Create;
will the class actually exist.
to do this properly you should declaire two function

Code: [Select]

Procedure TMyClass.AfterConstruction;
begin
  CecordInClass:= TCecordInClass.Create;
end;
Procedure TMyClass.BeforeDestruction;
begin
  CecordInClass.Destroy;
end;
  These are declare it TObject so you will need to add override to your  declaration

Code: [Select]

TMyClass = class
    CecordInClass : TCecordInClass;
    Procedure BeforeDestruction; override;
    Procedure AfterConstruction; override;
    function classfunction : Boolean;
    procedure classprocedure(const const1, const2, const3 : WideString);
  end;


[TheProgrammer]

Thanks for All!Köszönöm a segítséget!

This is my solution 1:
1. megoldásom:

Code: [Select]

//Unit:
   TRecordInClass = record
     Var1, Var2 : String;
   end;

  TMyClass = class
    RecordInClass : TRecordInClass;
    constructor Create;
  end;


constructor TMyClass.Create;
begin
RecordInClass.Var1 := 'xy';
RecordInClass.Var2 := 'yx';
end;

//----------
//Program:
procedure TForm1.Button1Click(Sender: TObject);
begin
MyClass := TMyClass.Create;
Label1.Caption := MyClass.RecordInClass.Var1;
MyClass.Destroy; 
end;

This is my solution 2:
2. megoldásom:

Code: [Select]

//Unit:
   TClassInClass = Class
     Var1, Var2 : String;
     //Other
   end;

  TMyClass = class
    ClassInClass : TClassInClass;
    constructor Create;
    destructor Destroy;
  end;


constructor TMyClass.Create;
begin
ClassInClass := TClassInClass.Create;

ClassInClass.Var1 := 'xy';
ClassInClass.Var2 := 'yx';
end;

destructor TMyClass.Destroy;
begin
ClassInClass.Destroy;
end;

//----------
//Program:
procedure TForm1.Button1Click(Sender: TObject);
begin
MyClass := TMyClass.Create;
Label1.Caption := MyClass.ClassInClass.Var1;
MyClass.Destroy;
end;

[Carver413]

do not forget that which you create you must also destroy

[TheProgrammer]

Ok I write Destroy/destructor code...
Oké Írok lezáró részeket (Destroy)...