CODEWITHSUNDEEP
delphioverloadingrecordvarianttobject
user3670958
user3670958

Reputation: 29

Variant record instead of overloaded object type?

I'm working on a problem in which I need to dynamically size an array, upon which numerous operations are needed. I have successfully coded two classes, t_one and t_two:

tarray1 : array of longint;
tarray2 : array of single;
t_one = class(tobject)
  Public
  Myarray1 : tarray1;
  constructor create;
  destructor destroy;
  procedure oneofmany; 
end;
t_two = class(tobject)
  Public
  Myarray1 : tarray2;
  constructor create;
  destructor destroy;
  procedure oneofmany; 
end;

The two objects have nearly identical code except that Myarray1 is an array of single in one case and an array of longint in the other. Is the only way to make this into a single object to use variant arrays (which will slow things down)? A variant record is inefficient for what I'm doing as well. If I could say

case mysituation of
  integerdata : (myarray1 : tarray1);
  realdata: (myarray1 : tarray2);
end;

that would be what I mean, but obviously that syntax is anathema. Of course, there are places where method calls and function results need to know the data type, but once defined they're consistent. Thoughts? Use a variant array and suffer the slowdown?

Upvotes: 1

Views: 203

Answers (2)

user3670958
user3670958

Reputation: 29

Turns out the answer leads to solutions that get quite convoluted. There's a reason for strong typing! Because one cannot have multiple function return types with the same function name, one gets bogged down in similarly named functions for different argument types. If you try

var
  mypointer : pointer;
begin
  case argtype of
    integer: mypointer := @A;
    single : mypointer := @B;
end;

then you still need to type mypointer every time you use it. Turns out not to help a whole lot.

Upvotes: 1

MBo
MBo

Reputation: 80325

One of possible approaches - make the only class using generics

  TA<T> = class
  public
     Arr : TArray<T>;
     destructor destroy;override;
  end;
...
procedure TForm1.Button1Click(Sender: TObject);
var
  A: TA<Integer>;
  B: TA<Single>;
begin
  A := TA<Integer>.Create;
  B := TA<Single>.Create;
  A.Arr := [1,2,3];
  B.Arr := [Pi, Ln(2)];
  Memo1.Lines.Add(A.Arr[0].ToString);
  Memo1.Lines.Add(B.Arr[0].ToString);
end;

Upvotes: 3

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