[fpc-devel] type question

[peter green]

one trick if you wan't to keep a type but redefine the operators on it is to
wrap it in a single element record.

> -----Original Message-----
> From: fpc-devel-bounces at lists.freepascal.org
> [mailto:fpc-devel-bounces at lists.freepascal.org]On Behalf Of Marc
> Weustink
> Sent: 14 October 2006 16:42
> To: FPC developers' list
> Subject: Re: [fpc-devel] type question
>
>
> Peter Vreman wrote:
> >> On Saturday 14 October 2006 15:55, Marc Weustink wrote:
> >>> Hi,
> >>>
> >>> if I define 2 types like:
> >>>
> >>> type
> >>>   MyA = type string;
> >>>   MyB = type string;
> >>>
> >>> are MyA and MyB considered as the same type ?
> >> No, you are explicitly marking them as a new type. This is a very cool
> >> feature
> >> of Pascal you wont find in many other languages.
> >>
> >> (For instance, you could use it to create a new integer-type
> for little-
> >> and
> >> big-endian numbers, ensuring that you _never_ directly assign a
> >> little-endian
> >> number to a big-endian one, or vice versa)
> >
> > For the compiler the types are not equal anymore, but they are still
> > compatible for implicit type conversion. This has mainly impact on
> > overload choosing and parameter passing. Normal assignments
> using ':=' are
> > not affected because of the still available implicit type conversion.
>
> I came to this when I wanted to do operator overloading on them. The
> compiler complained that you cannot overload for equal types.
>
> So I wanted first to know if it are equal types or not.
>
> Next question: Should operator overloading be possible on such types ?
>
> Marc
>
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