create c# like classes in delphi

[noeska]

In C# you have special classes like String that work like this

String MyString = "    This is an test string   ";
Console.WriteLine(MyString.Trim());

It class like the String class is created like this:
http://www.codeproject.com/useritems...t_operator.asp

Is it possible to use something like this in Delphi ((win32) 2005/turbo)? I now something like this is possible for arrays. E.g. MyObject[i] instead of MyObject.Lines[i].

Thanks for your answers in advance.

[JSoftware]

code for Turbo Delphi win32

type
 MyString = record
  data: string;
  function Trim: MyString;
  class operator implicit(a: string): MyString;
  class operator implicit(a: MyString): String;
 end;

{ MyString }

class operator MyString.implicit(a: string): MyString;
begin
   result.data := a;
end;

class operator MyString.implicit(a: MyString): String;
begin
   result := a.data;
end;

function MyString.Trim: MyString;
begin
   //trim stuff here
   result := self;
end;

begin
   a := '    This is an test string   ';
   writeln(string(a.Trim()));
end;

[noeska]

Where can i find a tutorial on this class operator constructions? I get lost in the delphi help.

PS: i seem to have posted this in the wrong forum. It should have been posted in the delphi forum. Sorry for that.

[WILL]

[size=9px]Easily moved. [/size]

[JSoftware]

I haven't found any valuable online resources. I learnt everything through the help file. Atm it doesn't work but searching for operator overloading with filter set to language: delphi you should find what you need.

if you need a list of operators available to overload then heres a shortened list which is contained in my Tvector4f record:

  class operator add(a,b: tvector4f): tvector4f;
  class operator add(a: tvector4f; b: single): tvector4f;
  class operator add(a: single; b: tvector4f): tvector4f;
  class operator Subtract(a,b: tvector4f): tvector4f;
  class operator Subtract(a: tvector4f; b: single): tvector4f;
  class operator Subtract(a: single; b: tvector4f): tvector4f;
  class operator Multiply(a,b: tvector4f): tvector4f;
  class operator Multiply(a: tvector4f; b: single): tvector4f;
  class operator Multiply(a: single; b: tvector4f): tvector4f;
  class operator Divide(a,b: tvector4f): tvector4f;
  class operator Divide(a: tvector4f; b: single): tvector4f;
  class operator Divide(a: single; b: tvector4f): tvector4f;
  class operator Equal(a,b: tvector4f): boolean;
  class operator NotEqual(a,b: tvector4f): boolean;
  class operator Implicit(a: tvector4f): string;

If you use operator overloading for classes then you'll have to create the result yourself

[cronodragon]

That new feature of operator overloading in Delphi is very interesting.

I would really like to have arithmetic assigners, like +=, *= in Java. But how would them be in Pascal? Something like +:= or :*=... hehe, looks like a rabbit :lol:

[JSoftware]

fpc supports prefix operators(?) like c like +=, -=, *=,...

[noeska]

can you also do operator overloading in fpc?

[savage]

can you also do operator overloading in fpc?

Yes it's been part of FPC way before Delphi got it.

[JSoftware]

operator overloading in fpc is done outside type definitions like this

[pascal]interface

type
tvector = ...
end;

operator /(a: tvector4f; b: single)result: tvector4f;
operator *(a: tvector4f; b: single)salmon: tvector4f;

implementation

operator /(a: tvector4f; b: single)result: tvector4f;
begin
result := vector4f(a.x/b,...);
end;

operator *(a: tvector4f; b: single)salmon: tvector4f;
begin
salmon := vector4f(a.x*b,...);
end;[/pascal]