const

[Sean Kelly]

== Quote from Oskar Linde (oskar.lindeREM at OVEgmail.com)'s article
> Walter Bright wrote:
> > I appreciate the time and effort you made to explain your thoughts. I'll
> > try and answer them.
> Thank you for your explanation. It must be quite an effort battling all
> the negativism against it. I'll try to make this a constructive post.
> > Benji Smith wrote:
> >> CONST
> [snip]
> > I understand your and others' frustration with const, and here's what I
> > think it is based on:
...

Well said.  Some questions below.

...
> Now, I will not discuss the keywords used for reference constancy, but I
> think the keyword used to declare constants should be "const". Apart
> from being how it already almost works in D2, it would have the major
> advantage of making:
> const x = 5;
> mean exactly the same thing in D1 and D2!
> So, without any loss of power, transitivity or anything else, one can
> simplify the language and make the constancy of plain data compatible
> between D2 and D1.

I think the need for const vs. invariant in D 2.0 is that the compiler isn't
smart enough to know when the referenced data should actually never
change, and because a bunch of interesting optimizations are available
when the data really doesn't ever change, we have a keyword to hint to
the compiler that this is true.  It's much like "register" in C/C++.  That
said, I'm still not convinced that it's a good idea to allocate an additonal
keyword simply to convey this information to the compiler.  I'd still like
to believe that there's a better way, and like "register", I expect "invariant"
to be rendered completely useless at some point in the future.


Sean