Forward Class in different Units
lazarus / 21-General

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Weitentaaal · 2023-02-22 09:17

Hello,

is it Possible to Split this unit up into two parts, where each holds
a Class.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i MyClass1 =
Class; MyClass2 = class;private   class1: TMyClass1;end; MyClass1 =
classprivate   class2: TMyClass2;end; 
curretnly i have both classes (MyClass1, MyClass2) in the same unit. i
want to seperate them into two different units. Is that possible ?

thanks in advance

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marcov · 2023-02-22 09:32

No.

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Weitentaaal · 2023-02-22 09:58

ok thanks

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howardpc · 2023-02-22 18:59

I agree with Marco.


However, if you slightly redesign your classes using a base class, and
jump through a few hoops you can achieve a close-coupled TClass1 and
TClass2 in different units.
Here are the two example units:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
uClass1andBase; {$mode ObjFPC}{$H+} interface uses  Classes; type  
TBaseClass = class(TObject)  protected    FClass1: TBaseClass;   
FClass2: TBaseClass;  public    procedure ShowFClassType;   
destructor Destroy; override;  end;   TClass1 = class(TBaseClass) 
public    constructor Create;  end; var  FInitialised1:
Boolean=False;  FInitialised2: Boolean=False; implementation uses 
uClass2; { TBaseClass } destructor TBaseClass.Destroy;begin 
FClass1.Free;  FClass2.Free;  inherited Destroy;end; procedure
TBaseClass.ShowFClassType;begin  WriteLn('This class is type ',
ClassName);  case Assigned(FClass2) of    True:  WriteLn('FClass2 is
type ', FClass2.ClassName);    False: WriteLn('FClass2 is Nil'); 
end;  case Assigned(FClass1) of    True:  WriteLn('FClass1 is type ',
FClass1.ClassName);    False: WriteLn('FClass1 is Nil');  end;end; {
TClass1 } constructor TClass1.Create;begin  FInitialised1 := True; 
FClass1 := Nil;   if not FInitialised2 then begin    FClass2 :=
TClass2.Create;    FInitialised1 := False;  end;end; end.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
uClass2; {$mode ObjFPC}{$H+} interface uses  Classes,
uClass1andBase; type   TClass2 = class(TBaseClass)  public   
constructor Create;  end; implementation { TClass2 } constructor
TClass2.Create;begin  FClass2 := Nil;  FInitialised2 := True;   if not
FInitialised1 then begin    FClass1 := TClass1.Create;   
FInitialised1 := True;  end;end; end.
Here is the program needed to exercise the two units:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
CoupledClasses; {$IFDEF MSWINDOWS} {$AppType  console}  {$ENDIF} uses 
uClass1andBase, uClass2; var  c1: TClass1;  c2: TClass2; begin  c1 :=
TClass1.Create;  c1.ShowFClassType;   WriteLn;   c2:= TClass2.Create; 
c2.ShowFClassType;   WriteLn('Press Enter to exit');  ReadLn;  
c1.Free;  c2.Free;end.