DIP62: Volatile type qualifier for unoptimizable variables in embedded programming

[Johannes Pfau via Digitalmars-d]

Am Tue, 15 Jul 2014 21:16:20 +0000
schrieb "bearophile" <bearophileHUGS at lycos.com>:

> Johannes Pfau:
> 
> > //In runtime:
> > enum int* SOME_REG = 0xFFFF;
> >
> > //In user code
> > peek(SOME_REG);
> > poke(SOME_REG);
> > *SOME_REG = 1; //Oops, forgot poke! This is not acceptable
> 
> Perhaps this syntax:
> 
> volatile enum int* SOME_REG = 0xFFFF;
> 
> Could turn this in a syntax error (only peek/poke are allowed to 
> write and read from this address):
> 
> *SOME_REG = 1;
> 
> Bye,
> bearophile

You just reinvented this DIP ;-)

Once you add a volatile type qualifier, there's no need to use
peek/poke. The compiler can then easily detect reads/writes to these
variables and do the right thing.

The DIP may seem complicated cause it considers overloading,
transitivity and similar stuff. In practice almost nobody will use
these features. But if I had not specified them Walters first question
would have been "How does it interact with overloading" ;-)