KennyTM~ wrote:
On Dec 7, 09 04:30, Don wrote:
KennyTM~ wrote:
On Dec 7, 09 00:23, Andrei Alexandrescu wrote:
Is there any good use of unary +? As an aside, Perl programs do use it
occasionally for syntactic disambiguation :o).
Andrei
Yes, when you want to port the Boost Spirit parser :o) (OK that's an
abuse.)
Well the unary + can help to emphasize "it's a positive number", and
1.0e+10 is already a form of "unary +" (not the operator).
Removing the unary + doesn't lose much, but it doesn't gain much
either, and with it already present in all other languages, I don't
see a good reason to change it.
I think + should be added to the syntax for numeric literals, and in all
other cases unary + should be dropped.
Ie,
x = +0.78; should remain legal.
But
y = +x; should not.
And likewise,
x = +(+0.78); should be illegal.
Overloading + is odd, too. Currently:
+x;
creates a "has no effect" error if x is a built-in type. But if x has an
overloaded unary +, it might have side-effects. So it useful ONLY for
operator abuse!
import std.math;
auto theta1 = +PI/6;
auto theta2 = -PI/8;
Good one.
