Delphi 如何测试使用Move复制类型是否安全
我正在编写一个通用向量类型:Delphi 如何测试使用Move复制类型是否安全,delphi,Delphi,我正在编写一个通用向量类型: type TBigVector<T: record> = class private FSize: Integer; FEntries: TArray<T>; function GetEntry(Index: Integer): T; procedure SetEntry(Index: Integer; const Value: T); procedure SetSize(Value: In
type
TBigVector<T: record> = class
private
FSize: Integer;
FEntries: TArray<T>;
function GetEntry(Index: Integer): T;
procedure SetEntry(Index: Integer; const Value: T);
procedure SetSize(Value: Integer);
public
constructor Create(ASize: Integer);
property Size: Integer read FSize write SetSize;
property Entry[Index: Integer]: T read GetEntry write SetEntry; default;
procedure Zeroise;
function ToArray: TArray<T>;
end;
现在,对于像
Double
和我定制的Complex
类型这样的类型,我可以这样做。我知道它们是不受管理的,而且原始内存拷贝不会造成任何困难。我想做的是添加一个运行时检查,可能只在调试版本中调用,它强制执行T
没有托管类型的约束。我该怎么做呢?我会这样做:
TDoubleBigVector = class(TBigVector<Double>)
....
end;
TComplexBigVector = class(TBigVector<Complex>)
....
end;
program SO21753006;
{$APPTYPE CONSOLE}
uses
TypInfo,
Windows,
SysUtils;
type
TProblemRecord1 = record
I : Integer;
S : String;
end;
TProblemRecord2 = record
Obj : TObject;
end;
TGoodRecord = record
I : Integer;
K : Double;
S : Array[0..10] of Char;
end;
TBigVector<T: record> = class
private
FSize: Integer;
FEntries: TArray<T>;
function GetEntry(Index: Integer): T;
procedure SetEntry(Index: Integer; const Value: T);
procedure SetSize(Value: Integer);
public
constructor Create(ASize: Integer);
property Size: Integer read FSize write SetSize;
property Entry[Index: Integer]: T read GetEntry write SetEntry; default;
procedure Zeroise;
function ToArray: TArray<T>;
end;
function RecordHasNoManagedTypes(Typ : PTypeInfo) : Boolean;
var
TypeData : PTypeData;
begin
Assert(Assigned(Typ));
Result := True;
// only check if we have a record, or else we have a value type
if Typ.Kind = tkRecord then
begin
TypeData := GetTypeData(Typ);
Result := TypeData.ManagedFldCount = 0;
end;
end;
{ TBigVector<T> }
constructor TBigVector<T>.Create(ASize: Integer);
begin
Size := ASize;
end;
function TBigVector<T>.GetEntry(Index: Integer): T;
begin
end;
procedure TBigVector<T>.SetEntry(Index: Integer; const Value: T);
begin
end;
procedure TBigVector<T>.SetSize(Value: Integer);
begin
SetLength(FEntries, Value);
end;
function TBigVector<T>.ToArray: TArray<T>;
begin
end;
procedure TBigVector<T>.Zeroise;
begin
Assert(RecordHasNoManagedTypes(TypeInfo(T)), 'T must not have managed types!');
ZeroMemory(Pointer(FEntries), Size*SizeOf(T));
end;
var
Rec1 : TBigVector<Double>;
Rec2 : TBigVector<TGoodRecord>;
Rec3 : TBigVector<TProblemRecord1>;
Rec4 : TBigVector<TProblemRecord2>;
begin
try
Writeln('Double type');
Rec1 := TBigVector<Double>.Create(1);
Rec1.Zeroise;
Writeln('GoodRecord type');
Rec2 := TBigVector<TGoodRecord>.Create(10);
Rec2.Zeroise;
try
Writeln('Problemrecord1 type');
Rec3 := TBigVector<TProblemRecord1>.Create(10);
Rec3.Zeroise;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
try
Writeln('Problemrecord2 type');
Rec4 := TBigVector<TProblemRecord2>.Create(10);
Rec4.Zeroise;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
Readln;
end.
procedure TBigVector<T>.Zeroise;
begin
Assert(not RTTI.IsManaged(TypeInfo(T)), 'T must not have managed types!');
ZeroMemory(Pointer(FEntries), Size*SizeOf(T));
end;
更新2从XE7开始,您可以使用固有函数
System.IsManagedType(T)
。这将在编译时解决,导致零运行时开销
如果是IsManagedType(T),则断言(false,“T不是托管类型”)
不要执行断言(而不是(IsManagedType(t)),因为编译器将无法删除断言,但如果它不适用,它将删除
。@whosrdaddy是的。但我更愿意使用类型信息方法,以与Delphi的RTL相同的方式。我通常在构建时关闭新样式的RTTI。我很高兴看到这两种风格的答案。什么满足了我个人的需要s是一回事,但我怀疑不同风格的答案可能对其他人有价值。类类型是非托管的,没有特殊的编译器支持。Initialize
和Finalize
对它们没有操作,复制它们只会复制原始位。动态数组是托管的。您看到的行为对它们来说很有意义我。+1谢谢。您的回答让我找到了Rtti.IsManaged
。这可能是一个值得信赖的好服务。问得好,回答得好。有人知道为什么System.Rtti.IsManaged
不在系统中。TypInfo
?此函数没有使用任何Rtti内容…托管类型不包括TObjects
,至少对于非arc平台是这样。另请参见。@whosrdaddyTObject
对于非arc平台是不受管理的。因此使用ManagedFldCount
非常适合这个问题。我想也许你应该编辑答案以反映这一点。然后我会接受。
procedure TBigVector<T>.Zeroise;
begin
Assert(not RTTI.IsManaged(TypeInfo(T)), 'T must not have managed types!');
ZeroMemory(Pointer(FEntries), Size*SizeOf(T));
end;