I am trying out the examples at
http://wiki.freepascal.org/Enumerated_types but
The following simple program will raise compiler error "No type info available for this typ"

I am using Lazarus 1.8.0  FPC 3.0.4   x86_64-Win64-win32/win64

program testenum;
uses typinfo, classes, sysutils;
type
   TMonthType = (January=1, February, May=5,June, July);
var i : int32;
     s : String;
begin
   for i := Ord(Low(TMonthType)) to Ord(High(TMonthType)) do
     begin
        s:= GetEnumName(TypeInfo(TMonthType), Ord(i)); <- compiler error
pointed at the word TypeInfo
        Writeln(i.ToSTring+' -> '+s);
     end;
   readln;
end.
However, if I change to
   TMonthType = (January, February, May,June, July);

The compiler error will disappear.

Is this kind of enumerated type with constant assignment not supported by FPC 3.0.4?

   TMonthType = (January=1, February, May=5,June, July);

Dennis

No, only normal enumerated types can be used like that.

Michael.

Dennis schrieb am Mo., 23. Juli 2018, 12:24:

The enumeration type itself is supported, however TypeInfo() and thus GetEnumName() and friends are not.

Regards,
Sven

Instead of GetEnumName, you may use ReadStr and WriteStr - the IO functions use their separate tables, which are generated correctly even for enums with assignments.

Martok schrieb am Mo., 23. Juli 2018, 17:15:

Though you'll get an access violation if you use a value that's not part of the enum (in the example this will happen when the loop reaches the value 3).

Regards,
Sven

Sven Barth wrote

Though you'll get an access violation if you use a value that's not part of the enum (in the example this will happen when the loop reaches the value 3).

Not an AV - an IOError, so it's easy and safe to catch.

I use stuff like this, with aValue being of a generic type:
  {$IOChecks OFF}
  WriteStr(Result, aValue);
  if IOResult = 107 then
    Result:= '';
  ReadStr(aStr, a);
  Result:= IOResult  106;
  if Result then
    aValue:= a;

Turns out this is currently also the *only* typesafe way to check if an arbitrary ordinal is a valid member of an enum type. But that's a different story ;-)

No only that, the following also gives error
  for a in TMonthType do
     begin
       //a won't be assigned the proper values     end;