On Sat, Jul 13, 2019 at 2:37 PM Ondrej Pokorny <[email protected]> wrote:
> I do exactly the same - check the low/high bounds in a type helper :)
> Yes, and I am tired of typing it as well :)
>
You can pretty easily write a generic function that will work on pretty
much any enum for this, BTW:
program Example;
{$mode Delphi}
uses TypInfo, SysUtils;
function TryConvert<T>(const Value: SizeInt): T; inline;
begin
if (Value >= SizeInt(Low(T))) and (Value <= SizeInt(High(T))) then
Result := T(Value)
else
raise EConvertError.Create(
Format(
'Invalid value for %s : %d', [
PTypeInfo(TypeInfo(T))^.Name,
Value
]
)
);
end;
type
Letter = (A, B, C);
begin
WriteLn(TryConvert<Letter>(0));
WriteLn(TryConvert<Letter>(1));
WriteLn(TryConvert<Letter>(2));
// Exception!
WriteLn(TryConvert<Letter>(3));
end.
The exception printing "EConvertError: Invalid value for Letter : 3", of
course.
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