前向声明不能跨单元工作。当一个单元转发声明一个记录/类时,同一单元也必须定义该记录/类。
我建议定义一个IMesh
接口TMesh
实现,然后有TVertices
and TTriangleFaces
use IMesh
代替TMesh
直接地。这样,就不存在循环引用,并且接口可以公开所需的任何字段值的属性。和TComponent
禁用已实现接口的引用计数,因此内存泄漏不是问题。
MeshIntf.pas:
unit MeshIntf;
interface
type
IMesh = interface(IInterface)
['{30315BC6-9A2E-4430-96BB-297D11C9DB5D}']
// methods for performing common tasks...
// properties for reading/setting needed values...
end;
implementation
end.
顶点.pas:
unit Vertices;
interface
uses
System.Types, System.Generics.Collections, MeshIntf;
type
TVertex = record
Point: TPoint3D;
//other fields
end;
TVertices = class(TList<TVertex>)
public
Mesh: IMesh;
constructor Create(const AMesh: IMesh); reintroduce;
procedure DoSomethingWithAllVertices;
//other methods
end;
implementation
constructor TVertices.Create(const AMesh: IMesh);
begin
inherited Create;
Mesh := AMesh;
end;
procedure TVertices.DoSomethingWithAllVertices;
begin
// use properties/methods of Mesh as needed...
end;
end.
TriangleFaces.pas:
unit TriangleFaces;
interface
uses
System.Generics.Collections, MeshIntf;
type
TTriangleFace = record
Vertices: Array[0..2] of Integer;
//other fields
end;
TTriangleFaces = class(TList<TTriangleFace>)
public
Mesh: IMesh;
constructor Create(const AMesh: IMesh); reintroduce;
procedure DoSomethingWithAllTriangleFaces;
//other methods
end;
implementation
constructor TTriangleFaces.Create(const AMesh: IMesh);
begin
inherited Create;
Mesh := AMesh;
end;
procedure TTriangleFaces.DoSomethingWithAllTriangleFaces;
begin
// use properties/methods of Mesh as needed...
end;
end.
Mesh.pas:
unit Mesh;
interface
uses
Classes, MeshIntf, Vertices, TriangleFaces;
type
TMesh = class(TComponent, IMesh)
public
Vertices: TVertices;
TriangleFaces: TTriangleFaces;
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
//other fields & methods, and IMesh implementation
end;
implementation
constructor TMesh.Create(AOwner: TComponent);
begin
inherited;
Vertices := TVertices.Create(Self as IMesh);
TriangleFaces := TTriangleFaces.Create(Self as IMesh);
end;
destructor TMesh.Destroy;
begin
Vertices.Free;
TriangleFaces.Free;
inherited;
end;
end.
如果你不需要TMesh
为了在设计时可供表单设计器和对象检查器使用,您应该从TInterfacedObject
代替TComponent
。但随后您需要进行一些小调整才能正确处理引用计数(其中TComponent
禁用)。尤其,TVertices
and TTriangleFaces
需要使用弱引用以免增加TMesh
的引用计数并导致内存泄漏(因为在这种情况下其引用计数将永远降至 0):
MeshIntf.pas:
unit MeshIntf;
interface
uses
System.Types;
type
TVertex = record
Point: TPoint3D;
//other fields
end;
IVertices = interface(IInterface)
['{97A70A11-C8B6-4DBC-807B-B9E0C6953B9E}']
// methods for performing tasks...
procedure DoSomethingWithAllVertices;
function GetVertex(Index: Integer): TVertex;
// properties for reading/setting values...
property Vertex[Index: Integer]: TVertex read GetVertex;
end;
TTriangleFace = record
Vertices: Array[0..2] of Integer;
//other fields
end;
ITriangleFaces = interface(IInterface)
['{A1ED479B-7430-4524-A630-FDDE212375BB}']
// methods for performing tasks...
procedure DoSomethingWithAllTriangleFaces;
function GetFace(Index: Integer): TTriangleFace;
// properties for reading/setting values...
property Face[Index: Integer]: TTriangleFace read GetFace;
end;
IMesh = interface(IInterface)
['{30315BC6-9A2E-4430-96BB-297D11C9DB5D}']
// methods for performing common tasks...
function GetVertices: IVertices;
function GetTriangleFaces: ITriangleFaces;
// properties for reading/setting values...
property Vertices: IVertices read GetVertices;
property TriangleFaces: ITriangleFaces read GetTriangleFaces;
end;
implementation
end.
顶点.pas:
unit Vertices;
interface
uses
System.Generics.Collections, MeshIntf;
type
TVertices = class(TInterfacedObject, IVertices)
private
// Delphi 10.1 Berlin adds [weak] support to all compilers,
// it was previously only available on the mobile compilers...
{$IFDEF WEAKINTFREF}
[weak] fMesh: IMesh;
{$ELSE}
fMesh: Pointer;
{$ENDIF}
fVertices: TList<TVertex>;
public
constructor Create(AMesh: IMesh);
destructor Destroy; override;
//other methods
// IVertices implementation
procedure DoSomethingWithAllVertices;
function GetVertex(Index: Integer): TVertex;
end;
implementation
constructor TVertices.Create(AMesh: IMesh);
begin
inherited Create;
fMesh := {$IFDEF WEAKINTFREF}AMesh{$ELSE}Pointer(AMesh){$ENDIF};
fVertices := TList<TVertex>.Create;
end;
destructor TVertices.Destroy;
begin
fVertices.Free;
inherited;
end;
procedure TVertices.DoSomethingWithAllVertices;
begin
// use properties of fMesh as needed...
// if WEAKINTFREF is not defined simply type-cast the Mesh
// pointer as IMesh(fMesh) when accessing its members...
end;
function TVertices.GetVertex(Index: Integer): TVertex;
begin
Result := fVertices[Index];
end;
end.
TriangleFaces.pas:
unit TriangleFaces;
interface
uses
System.Generics.Collections, MeshIntf;
type
TTriangleFaces = class(TInterfacedObject, ITriangleFaces)
private
// Delphi 10.1 Berlin adds [weak] support to all compilers,
// it was previously only available on the mobile compilers...
{$IFDEF WEAKINTFREF}
[weak] fMesh: IMesh;
{$ELSE}
fMesh: Pointer;
{$ENDIF}
fFaces: TList<TTriangleFace>;
public
constructor Create(AMesh: IMesh);
destructor Destroy; override;
//other methods
// ITriangleFaces implementation
procedure DoSomethingWithAllTriangleFaces;
function GetFace(Index: Integer): TTriangleFace;
end;
implementation
constructor TTriangleFaces.Create(AMesh: IMesh);
begin
inherited Create;
fMesh := {$IFDEF WEAKINTFREF}AMesh{$ELSE}Pointer(AMesh){$ENDIF};
fFaces := TList<TTriangleFace>.Create;
end;
destructor TTriangleFaces.Destroy;
begin
fFaces.Free;
inherited;
end;
procedure TTriangleFaces.DoSomethingWithAllTriangleFaces;
begin
// use properties of fMesh as needed...
// if WEAKINTFREF is not defined simply type-cast the Mesh
// pointer as IMesh(fMesh) when accessing its members...
end;
function TTriangleFaces.GetFace(Index: Integer): TTriangleFace;
begin
Result := fFaces[Index];
end;
end.
Mesh.pas:
unit Mesh;
interface
uses
MeshIntf;
type
TMesh = class(TInterfacedObject, IMesh)
private
// note, these are *strong* references, not*weak* references!
fVertices: IVertices;
fTriangleFaces: ITriangleFaces;
public
constructor Create;
//other fields & methods
// IMesh implementation
function GetVertices: IVertices;
function GetTriangleFaces: ITriangleFaces;
end;
implementation
uses
Vertices, TriangleFaces;
constructor TMesh.Create;
begin
inherited;
fVertices := TVertices.Create(Self as IMesh);
fTriangleFaces := TTriangleFaces.Create(Self as IMesh);
end;
function TMesh.GetVertices: IVertices;
begin
Result := fVertices;
end;
function TMesh.GetTriangleFaces: ITriangleFaces;
begin
Result := fTriangleFaces;
end;
end.
只要确保你有一个不弱的IMesh
创建时在代码中的某处变量TMesh
对象,以便它保持活动状态,直到您不再需要它为止:
var
Meth: IMesh; // or a class member or a global, wherever you need it
Mesh := TMesh.Create;
...
Mesh := nil;
(正确的)引用计数将为您处理剩下的事情。