我希望能够从ST：TElementSet检查，添加和删除T：TElements。
type
TElements = (elA, elB, elC);
TElementSet = set of TElements;
TMyClass<T, ST> = class
property SetValue:ST;
end;
泛型不允许我告诉编译器T是枚举类型而ST是一组T。
RTTI使我能够将类型识别为tkEnumeration和tkSet - 但我不确定是否可以使用RTTI在两者之间建立严格的连接。这并不重要，因为我只需要通过序数值来旋转设置位。
问题是：我可以安全地使用Generics和RTTI，如果是这样 - 如何做到这一点？
将赞赏对现有技术的示例和/或参考。
答案 0 :(得分：5)
假设我们只处理连续的枚举（因为其他人没有正确的typeinfo且无法轻易处理），我们可以在没有typeInfo / RTTI的情况下完成此操作。
枚举为枚举中的元素设置了一个掩码。
例如，集合[elA，elC]等于00000101（从右到左）等于5。
要设置的位的索引等于enum + 1的序数值（因为第一个枚举值的序数为0，但它是第1位）。
由于我们不能在Delphi中设置单个位而只能在字节中设置，我们需要计算正确的值，从而导致包含以下代码：
set [enum div 8]：= set [enum div 8]或（1 shl（enum mod 8））
由于集合不能包含超过256个元素，因此我们也可以假设枚举值始终是字节的大小。处理不从0开始的枚举将需要更多的代码并读取typeinfo的最小值和最大值
这里有一些测试代码 - 我使用绝对技巧，但你也可以使用hardcast：
program GenericEnumSet;
{$APPTYPE CONSOLE}
type
TMyEnum = (elA, elB, elC);
TMySet = set of TMyEnum;
TEnumSet<TEnum,TSet> = record
value: TSet;
procedure Include(const value: TEnum); inline;
procedure Exclude(const value: TEnum); inline;
end;
procedure _Include(var setValue; const enumValue);
var
localEnum: Byte absolute enumValue;
localSet: array[0..31] of Byte absolute setValue;
begin
localSet[localEnum div 8] := localSet[localEnum div 8] or (1 shl (localEnum mod 8));
end;
procedure _Exclude(var setValue; const enumValue);
var
localEnum: Byte absolute enumValue;
localSet: array[0..31] of Byte absolute setValue;
begin
localSet[localEnum div 8] := localSet[localEnum div 8] and not (1 shl (localEnum mod 8));
end;
procedure TEnumSet<TEnum, TSet>.Include(const value: TEnum);
begin
_Include(Self.value, value);
end;
procedure TEnumSet<TEnum, TSet>.Exclude(const value: TEnum);
begin
_Exclude(Self.value, value);
end;
var
mySet: TEnumSet<TMyEnum,TMySet>;
myEnum: TMyEnum;
begin
mySet.value := [];
for myEnum := Low(TMyEnum) to High(TMyEnum) do
begin
mySet.Include(myEnum);
Assert(mySet.value = [Low(TMyEnum)..myEnum]);
end;
for myEnum := Low(TMyEnum) to High(TMyEnum) do
begin
mySet.Exclude(myEnum);
if myEnum < High(TMyEnum) then
Assert(mySet.value = [Succ(myEnum)..High(TMyEnum)])
else
Assert(mySet.value = []);
end;
Readln;
end.
我将实施其他方法和错误检查作为读者的练习。
答案 1 :(得分：1)
这很快，由于Delphi具有泛型而非模板，您不会获得任何编译时安全性，但我认为这应该涵盖运行时的所有基础。
program GenericSetInclusion;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils,
System.TypInfo,
System.Rtti;
type
TElm = (elFoo, elBar, elXyz);
TElms = set of TElm;
TOrd = 7..150;
TOrds = set of TOrd;
type
SafeSet = record
class procedure Include<ST, T>(var s: ST; const e: T); static;
end;
{ SafeSet }
class procedure SafeSet.Include<ST, T>(var s: ST; const e: T);
var
ctx: TRttiContext;
typ1: TRttiType;
typ2: TRttiType;
styp: TRttiSetType;
etyp: TRttiOrdinalType;
ttyp: TRttiOrdinalType;
tmp: set of 0..255;
o: 0..255;
i: integer;
begin
ctx := TRttiContext.Create();
typ1 := ctx.GetType(TypeInfo(ST));
if (typ1 = nil) then
raise EArgumentException.Create('SafeSet<ST, T>.Include: ST has no type info');
typ2 := ctx.GetType(TypeInfo(T));
if (typ2 = nil) then
raise EArgumentException.CreateFmt('SafeSet<ST=%s, T>.Include: T has no type info (most likely due to explicit ordinality)', [typ1.Name]);
if (not (typ1 is TRttiSetType)) then
raise EArgumentException.CreateFmt('SafeSet<ST=%s, T=%s>.Include: ST is not a set type', [typ1.Name, typ2.Name]);
styp := TRttiSetType(typ1);
if (SizeOf(ST) > SizeOf(tmp)) then
raise EInvalidOpException.CreateFmt('SafeSet<ST=%s, T=%s>.Include: SizeOf(ST) > 8', [styp.Name, typ2.Name]);
etyp := styp.ElementType as TRttiOrdinalType;
if (not (typ2 is TRttiOrdinalType)) then
raise EArgumentException.CreateFmt('SafeSet<ST=%s, T=%s>.Include: T is not an ordinal type', [styp.Name, typ2.Name]);
ttyp := TRttiOrdinalType(typ2);
case ttyp.OrdType of
otSByte: i := PShortInt(@e)^;
otUByte: i := PByte(@e)^;
else
raise EInvalidOpException.CreateFmt('SafeSet<ST=%s, T=%s>.Include: SizeOf(T) > 1', [styp.Name, ttyp.Name]);
end;
if (ttyp.Handle <> styp.ElementType.Handle) then
begin
if (((etyp is TRttiEnumerationType) and (not (ttyp is TRttiEnumerationType)))) or
((not (etyp is TRttiEnumerationType)) and (ttyp is TRttiEnumerationType)) then
raise EArgumentException.CreateFmt('SafeSet<ST=%s, T=%s>.Include: ST is not a set of T (ST is set of %s)', [styp.Name, ttyp.Name, etyp.Name]);
// ST is a set of integers rather than a set of enum
// so do bounds checking
if ((i < etyp.MinValue) or (i > etyp.MaxValue)) then
raise EArgumentException.CreateFmt('SafeSet<ST=%s, T=%s>.Include: %d is not a valid element for ST (ST is set of %s = %d..%d)', [styp.Name, ttyp.Name, i, etyp.Name, etyp.MinValue, etyp.MaxValue]);
end;
o := i;
FillChar(tmp, SizeOf(tmp), 0);
Move(s, tmp, SizeOf(ST));
System.Include(tmp, o);
Move(tmp, s, SizeOf(ST));
end;
procedure Test(const p: TProc);
begin
try
p();
WriteLn('Success');
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
end;
var
s: TElms;
o: TOrds;
begin
Test(
procedure
begin
SafeSet.Include(s, elFoo);
Assert(elFoo in s, 'elFoo not in s');
Assert((s - [elFoo]) = [], 's contains elements it should not');
SafeSet.Include(s, elBar);
Assert(elFoo in s, 'elFoo not in s');
Assert(elBar in s, 'elBar not in s');
Assert((s - [elFoo, elBar]) = [], 's contains elements it should not');
SafeSet.Include(s, elXyz);
Assert(elFoo in s, 'elFoo not in s');
Assert(elBar in s, 'elBar not in s');
Assert(elXyz in s, 'elXyz not in s');
Assert((s - [elFoo, elBar, elXyz]) = [], 's contains elements it should not');
end
);
Test(
procedure
begin
SafeSet.Include(o, 7);
Assert(7 in o, '7 not in o');
Assert((o - [7]) = [], 'o contains elements it should not');
end
);
Test(
procedure
begin
SafeSet.Include(s, 7);
Assert(False, '7 should not be in s');
end
);
Test(
procedure
begin
SafeSet.Include(o, elFoo);
Assert(False, 'elFoo should not be in o');
end
);
Test(
procedure
begin
SafeSet.Include(o, 1);
Assert(False, '1 should not be in o');
end
);
ReadLn;
end.
这为我输出以下内容，使用D10：
Success
Success
EArgumentException: SafeSet<ST=TElms, T=ShortInt>.Include: ST is not a set of T (ST is set of TElm)
EArgumentException: SafeSet<ST=TOrds, T=TElm>.Include: ST is not a set of T (ST is set of TOrd)
EArgumentException: SafeSet<ST=TOrds, T=ShortInt>.Include: 1 is not a valid element for ST (ST is set of TOrd = 7..150)