Casting an untyped pointer to a typed when using with New() and Dispose()

[PeaShooter_OMO 10]

type
  TMyRec = record
    Int : Integer;
    Str : String;
  end;
  PMyRec = ^TMyRec;

var
  LPointer : Pointer;
begin
  New(PMyRec(LPointer));
  PMyRec(LPointer)^.Int := 200;
  PMyRec(LPointer)^.Str := 'Blah';
  Dispose(PMyRec(LPointer));
end;

I do not know why this approach bothers me but for some reason it does. I am casting a Pointer to a PMyRec to use it with New() and Dispose().

 

I do not get a memory leak from this so I am assuming it will be operating correctly. Am I right?

 

Edit:

I understand that typed pointers are to be used with New() and Dispose(). This is just an experiment into the working of the memory around this and also New() and Dispose(). That's all.

Edited March 15 by PeaShooter_OMO

[DelphiUdIT 132]

If you must use NEW (so create a new variable), why don't declare it like a normal variable or a typed pointer? If you refer a record variable you don't need to allocate memory.

 

If you need to reference a pointer, this normally means that it's already assigned and you can cast without NEW or DISPOSE.

 

Another suggestion: in Delphi you don't need to "defererence" a typed pointer, the compiler do it for you:

 

var
  LPointer : Pointer;
begin
  New(PMyRec(LPointer));
  PMyRec(LPointer).Int := 200;
  PMyRec(LPointer).Str := 'Blah';
  Dispose(PMyRec(LPointer));
end;

var
  LPointer : PMyRec;
begin
  New(LPointer);
  LPointer.Int := 200;
  LPointer.Str := 'Blah';
  Dispose(LPointer);
end;

 

[PeterBelow 218]

3 hours ago, PeaShooter_OMO said:

type
  TMyRec = record
    Int : Integer;
    Str : String;
  end;
  PMyRec = ^TMyRec;

var
  LPointer : Pointer;
begin
  New(PMyRec(LPointer));
  PMyRec(LPointer)^.Int := 200;
  PMyRec(LPointer)^.Str := 'Blah';
  Dispose(PMyRec(LPointer));
end;

I do not know why this approach bothers me but for some reason it does. I am casting a Pointer to a PMyRec to use it with New() and Dispose().

 

I do not get a memory leak from this so I am assuming it will be operating correctly. Am I right?

 

 

 

It will work but there is no point in doing it this way. Declare LPointer as type PMyRec and work with that. Don't use C idioms with Delphi, that only confuses things.

[PeaShooter_OMO 10]

@PeterBelow @DelphiUdIT

I understand and edited my post.