Re: {pkgsrc-users} need help with C# -- how to deal with different time_t widths?

[Brian de Alwis <bsd%cs.ubc.ca@localhost>]

Hi Matthias.

On 9-Sep-2009, at 11:41 AM, Matthias Drochner wrote:
> > The lower-case are the primitive types, and
> > the System.* are their corresponding classes; C# will automatically
> > box/unbox them as necessary.
>
> What would be the advantage of using classes for integers?
> Passing integers by reference doesn't sound very efficient.
> (But anyway, since my problem is about modeling a C data
> structure in C# I guess that simple types are the way to go.)

Even if you specify the classes, I don't think the instances are  
actually passed by reference: the actual instances aren't mutable. The  
notations simply interchangeable.

> > #if TIMET_IS_32BITS
> >      UInt32 blah;
> > #else
> >      UInt64 blah;
> > #endif
>
> Thanks - this works.
> Unfortunately, the assumption that time_t fits into a pointer
> is also in exported interfaces of the underlying gtk-sharp
> library, so I needed some typecasts to compensate.

So GTK# actually provide the time_t by casting it as a pointer?  Yuck.

> I think a better fix would be to make the type used for
> time_t a 64-bit integer throughout the code, but that
> would be an interface change.
> Could you please have a look at pkgsrc/x11/gnome-sharp and
> check that my fix is correct?


I don't see any other way around it.  I'm not a System.Runtime.Interop  
expert, but I can't see a way to describe such platform-specific  
knowledge. I don't know how the code could detect whether the platform  
has 64-bit time_t values.

So that looks like it will work in the short-term.  These C# libraries  
won't be portable across platforms, but admittedly they weren't  
portable to NetBSD previously anyways :-)

I'm surprised this hasn't bitten people on 64-bit machine already  
though.  Linux on amd64 seems to have time_t = 64 bits [*].

Brian.

[*] https://lists.isc.org/pipermail/dhcp-users/2006-May/000644.html

--
"Amusement to an observing mind is study." - Benjamin Disraeli