如何在Delphi中使用RTTI或TypeInfo获取枚举的有效范围 [英] How can I get an enumeration's valid ranges using RTTI or TypeInfo in Delphi
问题描述
我在测试项目中使用RTTI来评估枚举值,最常见的是对象的属性.如果枚举超出范围,我想显示类似于评估/修改IDE窗口"显示的文本.类似于((超出范围)255").
I am using RTTI in a test project to evaluate enumeration values, most commonly properties on an object. If an enumeration is out of range I want to display text similar to what Evaluate/Modify IDE Window would show. Something like "(out of bound) 255".
下面的示例代码使用TypeInfo在使用 GetEnumName
时将枚举值以外的值显示为访问冲突问题.任何使用RTTI或TypeInfo的解决方案都会对我有所帮助,我只是不知道测试代码中的枚举类型
The sample code below uses TypeInfo to display the problem with a value outside the enumeration as an Access Violation when using GetEnumName
. Any solution using RTTI or TypeInfo would help me, I just don't know the enumerated type in my test code
program Project60;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils, TypInfo;
Type
TestEnum = (TestEnumA, TestEnumB, TestEnumC);
const
TestEnumUndefined = TestEnum(-1);
procedure WriteEnum(const ATypeInfo: PTypeInfo; const AOrdinal: Integer);
begin
WriteLn(Format('Ordinal: %d = "%s"', [AOrdinal, GetEnumName(ATypeInfo, AOrdinal)]));
end;
var
TestEnumTypeInfo: PTypeInfo;
begin
try
TestEnumTypeInfo := TypeInfo(TestEnum);
WriteEnum(TestEnumTypeInfo, Ord(TestEnumA));
WriteEnum(TestEnumTypeInfo, Ord(TestEnumB));
WriteEnum(TestEnumTypeInfo, Ord(TestEnumC));
WriteEnum(TestEnumTypeInfo, Ord(TestEnumUndefined)); //AV
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
ReadLn;
end.
推荐答案
使用 GetTypeData()
可以从 PTypeInfo
,例如:
Use GetTypeData()
to get more detailed information from a PTypeInfo
, eg:
procedure WriteEnum(const ATypeInfo: PTypeInfo; const AOrdinal: Integer);
var
LTypeData: PTypeData;
begin
LTypeData := GetTypeData(ATypeInfo);
if (AOrdinal >= LTypeData.MinValue) and (AOrdinal <= LTypeData.MaxValue) then
WriteLn(Format('Ordinal: %d = "%s"', [AOrdinal, GetEnumName(ATypeInfo, AOrdinal)]))
else
WriteLn(Format('Ordinal: %d (out of bound)', [AOrdinal]));
end;
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