On 2008-11-25 16:39:05 -0500, Andrei Alexandrescu
<[EMAIL PROTECTED]> said:
Russell Lewis wrote:
I'm of the opinion that we should make mixed-sign operations a
compile-time error. I know that it would be annoying in some
situations, but IMHO it gives you clearer, more reliable code.
The problem is, it's much more annoying than one might imagine. Even
array.length - 1 is up for scrutiny. Technically, even array.length + 1
is a problem because 1 is really a signed int. We could provide
exceptions for constants, but exceptions are generally not solving the
core issue.
Then the problem is that integer literals are of a specific type. Just
make them polysemous and the problem is solved.
I'm with Russel on this one. To me, a litteral value (123, -8, 0) is
not an int, not even a constant: it's just a number which doesn't imply
any type at all until you place it into a variable (or a constant, or
an enum, etc.).
And if you're afraid the word polysemous will scare people, don't say
the word and call it a "integer litteral". Polysemy in this case is
just a mechanism used by the compiler to make the value work as
expected with all integral types. All you really need is a type
implicitly castable to everything capable of holding the numerical
value (much like your __intuint).
I'd make "auto x = 1" create a signed integer variable for the sake of
simplicity.
And all this would also make "uint x = -1" illegal... but then you can
easily use "uint x = uint.max" if you want to enable all the bits. It's
easier as in C: you don't have to include the right header and remember
the name of a constant.
--
Michel Fortin
[EMAIL PROTECTED]
http://michelf.com/
