On Tue, 16 Aug 2022, Juha Manninen via fpc-devel wrote:
On Thu, Aug 11, 2022 at 9:37 PM Martin Frb via fpc-devel <
fpc-devel@lists.freepascal.org> wrote:
fpc code is still "unexpected".
It takes into account the MinValue
type TMyEnum = (a=5, b=7);
GetEnumName(pt, 5) // a
GetEnumName(pt, 6) // b // should be 7
if it is just the nth name, then it should start at 0 (or if needs be at
1).
And function GetEnumValue() is buggy.
It is not buggy.
It does not support enumerateds with gaps, because RTTI does not support enumerateds with gaps.
It never has.
So if something needs fixing, it's FPC that needs to give an error when you try
to get RTTI for an enum with gaps, and amend the documentation for
GetEnumValue and GetEnumName.
This lack of RTTI info is completely Delphi compatible, by the way.
The following program prints 'Property info is null'
---
program rttitest;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils, System.Classes,
TypInfo;
type
TFruitMore = (fmApple=1, fmOrange=3, fmBanana=5, fmGrapes, fmPear);
TMyClass = class(TComponent)
private
FFruit: TFruitMore;
Published
property Fruit : TFruitMore Read FFruit Write FFruit;
end;
var
I: Integer;
PI : PPropInfo;
EnumType: PTypeInfo;
aClass : TMyClass;
begin
aClass:=TMyClass.Create(Nil);
PI:=GetPropInfo(aClass,'Fruit',tkAny);
if PI=nil then
Writeln('Property info is null')
else if PI^.PropType=nil then
Writeln('Type info is null')
else
begin
EnumType:=PI^.PropType^;
I := GetEnumValue(EnumType, 'fmBanana'); // Returns 3
Writeln(I);
I := GetEnumValue(EnumType, 'fmGrapes'); // Returns 4 which is an
Writeln(I);
end;
Readln;
end.
---
If you change it to
EnumType:=TypeInfo(TFruitMore);
Delphi will even write a compile-time error:
[dcc32 Error] rttitest.dpr(29): E2134 Type 'TFruitMore' has no type info
So what you want to do is simply not supported.
Gaps in enums are an ugly hack to allow importing C enums.
Don't use it in proper pascal code.
Michael.
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
