On 08.02.2015 04:10, silvioprog wrote:
Hello,
I'm trying to port a Delphi code to FPC, and it has a structure like:
TType = class(TObject)
end;
TTest<T1; T2: TType> = class(TObject)
end;
TFoo = class(TType)
end;
TBar = class(TTest<string, TFoo>)
end;
I.e., T1 accepts any type, but T2 accepts _only_ TType and/or their
descendants.
I tried the following code in FPC:
TType = class(TObject)
end;
generic TTest<T1; T2: TType> = class(TObject)
end;
TFoo = class(TType)
end;
TBar = class(specialize TTest<string, TFoo>)
end;
But:
===
Compile Project, Target: project1.exe: Exit code 1, Errors: 2
Unit1.pas(30,34) Error: class type expected, but got "AnsiString"
Unit1.pas(30,47) Error: class type expected, but got "<erroneous type>"
===
If I declare "T2" instead of "T2: TType", it compiles, but using this
declaration, a programmer can use accidentally a non descendant type of
TType.
Is there an issue about this in bugtracker?
Looks like a bug. Please report.
As a workaround you can move the constraint to the first type instead of
the second and specialize with "<TFoo, string>".
Regards,
Sven
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