Delphi in a Nutshell

Name

Finalize Procedure

Syntax

procedure Finalize(var Buffer);
procedure Finalize(var Buffer; Count: Integer);

Description

The Finalize procedure cleans up strings, dynamic arrays, interfaces, Variants, and records or arrays that contain these types. Delphi automatically finalizes variables of string, dynamic array, interface, or Variant type, but if you allocate such types dynamically, you need to finalize the memory before freeing it.

If you are finalizing more than one item in an array, pass the count of the number of array elements as the Count parameter. The Count is the number of array elements, not the number of bytes to be freed.

Finalize is not a real procedure.

Tips and Tricks

• Dispose calls Finalize for you, so you need to call Finalize only when you free memory by calling FreeMem.

• The first argument to Finalize is not a pointer, but the actual variable or dereferenced pointer.

• Finalize must know the type of the buffer so it can determine how to finalize array and record members. If you are casting a generic Pointer, be sure you cast it to the correct type. Typecasting pointers is a common source of hard-to-locate bugs.

Example

type
  TSample = record
    Str: string;
    List: array of Integer;
    Intf: IUnknown;
    V: Variant;
  end;
  TSampleArray = array[0..MaxInt div SizeOf(TSample)-1] of TSample;
  PSampleArray = ^TSampleArray;

// See the Initialize procedure to see how to allocate a TSample array.

procedure FreeSamples(Samples: PSampleArray; Count: Integer);
begin
 Finalize(Samples^, Count); ...