[Vm-dev] AioPlugin: VMConstruction-Plugins-AioPlugin-EstebanLorenzano.19.mcz

[David T. Lewis]

On Sat, May 28, 2016 at 05:29:03AM +0800, Ben Coman wrote:
>  
> On Sat, May 28, 2016 at 1:52 AM, David T. Lewis <lewis at mail.msen.com> wrote:
> >
> > Hi Esteban,
> >
> > I missed the discussion here, but this does not look like a good change. The
> > values of AIO_R, AIO_W, and AIO_X are declared in a header file in the platforms
> > sources. They should also not be hard-coded in the image, which is what happens
> > when you define them as class variables in AioPlugin.
> 
> What is the preferred way to synchronise header values between the
> platform sources and the Image?
> 

Do not do that. Do not attempt to synchonize them. Use the actual values
in the header files. Do not assume that they will never change, and do not
assume that they they will be the same on all platforms.

For example, you can write this, because it invokes the actual C language
definition of 'AIO_X' as defined in an external header file, and it uses 4
as a default for VM simulation:

    flags := flags bitOr: (self cCode: 'AIO_W' inSmalltalk: [4])

But you should not write the following, where AIO_X is a class var set to 4.
It looks prettier, but it is wrong because the value of AIO_W is hard coded
in a class initialization in the image:

    flags := flags bitOr: AIO_W

Pretty code is nice, but it is more important that it be correct.

Dave